Ok, now for my opinion.
I voted for option D - 1 + 2 + 3.
I'm going to explain this by telling you a little story.
I own quite a few reptiles and quite a few species. I think it was 45 animals, ranging from corns and house snakes to royals, rainbow boas, geckos, legless lizards and the apple of my partner's eye, an Argentine Tegu.
I breed the leopard geckos. Every adult has a name, every one of them is a beloved pet, and I can sit there and tell you that Lesuth is a lardbucket who likes to cop an attitude but she's not so bad; that Kurhah is mad as a pair of trousers, but oh he has a gorgeous feminine head... I can tell you a little "oh, so and so did such and such" story for each and every one of them. I LOVE them - they're my "kids" and I feel towards them the same warm fuzzies I feel towards my cats and indeed the people I care about. Two of the girls I bred this year, Keid and Chara, are babies that hatched here in this house. I've known them since I carefully scooped their eggs up out of the laying boxes. They're no special morph - just a couple of hypo girls. Keid is the first baby we ever hatched out, and oh, she could scream her head off and HATED me to start with.
Just over a week ago - on the Thursday night before Good Friday - I noticed Keid seemed to be having trouble with the clutch of eggs in her. She'd laid two... but there was a third big one in there. I gave her extra calcium, I put her in an isolation tub, and planned to call the vet in the morning. Next morning, gave her more calcium, and thought she seemed to be doing much better - the egg had shifted a bit in her belly, and she was strong enough to spit half the mouthful of calcium slurry all over me (so she got more). I made a judgement call - that I'd go out and pick up some more liquid calcium and some slurry-able kitten chow - that sort of stuff - and then phone the vet just to have her checked on.
When I got home, Keid - my first hatched baby and an animal I loved - had died. I'm kicking myself for breeding her even though she appeared healthy at the beginning of the year. It made me cry when I discovered that her last two eggs had moulded, because they represented a piece of her. I have one egg in the incubator from her, and I just hope it hatches out as a female so I can keep it.
And thinking about it last night... if there had been some magical way to 'trade' the death - for one of my other animals (completely healthy and fit, NAMED pets who I know better than I know my neighbours) to die in order for THAT gecko to live... I can point my finger at a dozen that I wouldn't have any hesitation to have traded for her life. I can choose another ten that I'd have to think about for a while, based on them being either investment animals or slightly more emotionally valuable to me.
Out of forty-five reptiles I own, I think there's only ten or twelve that I would not have sacrificed to save her, and that's because I love those animals as much as I loved her.
Conversely... if I plan to produce, say, forty leopard gecko hatchlings this year, and breed my girls accordingly - and then I wind up with eighty because everyone decides to give me eight clutches instead of four... yes, I DO have a "triage" value system. In this example, I have resources to produce, feed and keep forty hatchlings. I do not have resources enough to produce, feed and keep eighty hatchlings healthy. I would rather remove the surplus hatchlings before they drain my resources than risk the lives of all the hatchlings.
This year, we have made arrangements with a shop that will buy any "normal" morph leopard geckos from us straight out of the egg, no guarantee of feeding or health - for a pittance, in store credit, but at least they're not being culled and fed to the tegu.
This frees up my resources to go towards the babies who are going to 'pay their own way' in my collection - the ones I can sell to individuals and at least pay for the food they consume while they're with me, and hopefully for the food their parents consumed to make them. The BABIES are livestock, not pets. If I overproduce and don't have an outlet, then I do not have an intrinsic problem with taking the less profitable offspring and humanely euthanising them - it's better than the entire year's set of babies failing to thrive because I tried to stretch myself too far - and I'm sure I can find something that will eat baby geckos so that the nutrition they represent is not wasted.
Only the adults are pets, not livestock.
Sometimes babies unintentionally make the transition between livestock and pet. We have two little girls - last year's babies - who were not originally going to stay. Wednesday had a home planned, but it fell through. I sorted out another home for her. That one fell through too. Now, because I suspect she's a Keid baby (at least, it's as likely as not and at least I can pretend she is) ... she has a home here for life. Never mind I'd gotten attached to her anyhow. The other little girl, Maybe, she stayed because I spent so much time and energy trying to get her to thrive - so much so that she, along with the other eleven or so babies that didn't make it, have shaped my non-feeder policy (which is, in short, if it won't feed within a reasonable time frame, it will go. I will NOT let another hatchling suffer by my waiting too long to euthanise). She never stopped trying to bite me, so we thought "maybe she'll live." She has.
Same goes for my mice. I have a couple of adult females I love to bits - they're friendly, they're nice, and they produce nice, friendly females. Those two females are pets. However... their babies are there to be fed to snakes. That's exactly what I produce them for. The babies are livestock.
My corns? The ones I've got now are pets. The ones I breed will be livestock unless they're my own personal keepers (at which point they become pets). Babies that don't thrive won't be forced to suffer and starve. And if I plan for forty-five hatchlings and wind up with ninety... the babies that can't pay for the cost of feeding them will not stay either. Either they'll be sold straight out of the egg to a shop willing to take them on or they'll be euthanised and used to pay for the cost of feeding someone else.
For me... death is not evil, it is not a punishment to be feared. Euthanising one animal so that another animal can live - regardless of WHY you chose that one animal to die (because it's the wrong colour, because it's unhealthy, because it looks too much like this or that) - is not intrinsically wrong as far as I am concerned.
The only wrong, to me, is when a death is unnecessarily painful or stressful to the animal - or the death is wasted.