Answer: Option D
:
D
Fusion of male and female gametes during sexual reproduction forms a zygote which undergoes various stages of development to form a new individual. Therefore, it takes a long time for completion as compared to asexual methods of reproduction like binary fission, budding, fragmentation, etc. The offspring born through sexual reproduction are not identical to their parents but resemble them. This is because of the variation induced in the zygote due to exchange of genetic material. In lower organisms, the sexes are not fixed. For example in clown fish, sex literally depends on how big they are. The largest fish among the lot is designated as the breeding female while the second largest fish is always the breeding male. Upon death of the breeding female, the breeding male simply turns into the breeding female and replaces her. Sexual reproduction leads to genetic recombination. Sexual reproduction produces new and unique combinations of maternal and paternal alleles in each offspring. That leads to a great diversity of individuals in the population. Natural selection can then act on the population to give some individuals greater fitness than others, leading to changes in the population over time.