It’s b because its shown in the question read it again ,and you’ll see
Bonjour,
1. Arteries carry blood from the heart to the rest of the body, whereas veins carry blood from the rest of the body back to the heart.
2. Almost all arteries carry oxygenated blood and almost all veins carry deoxygenated blood.
3. Arteries have a thick elastic muscle layer, whereas the muscle layer for veins is much thinner.
It might be chemical to mechanical to electrical
Apomictic refers to plants and it means the offspring is genetically identical to the parent. Automictic means that gametes fuse after meiosis - which means offspring are genetically not identical to parents.
I'd go with A, Nucleus. I hope this helps!