A) 12 is the answer because sex cells have half as many chromosomes as the offspring will have, half from the mother, the other half from the father.
I was looking for an answer and I found this. I hope this helps in some way.
Answer:
It introduces the body to a virus strand(s) to initiate internal resistance, which is created after a variety of metabolical processes. The idea is that the body would develop immunity to the virus without actually "getting" the virus.
Explanation:
I believe it would be sedimentary, since layers are used. Hopefully this helps :)