I also believe the answer is A.
Answer:
Sexual reproduction involves two parents and the joining of male and female gametes during fertilisation. The offspring inherit a mixture of genes from both parents, so are different to each other and their parents. In asexual reproduction there is only one parent. The offspring are clones of the parent and each other.
It has more similarity to fossils in layer A than layer D.
Answer: Sex cell is the correct answer.
