During their development, many organisms look similar, suggesting that very different organisms may have a common ancestor. - Think of the human fetal neural / spine development which mirrors other species.
C. during their development, many organisms look similar, suggesting that very different organisms may have a common ancestor.
Explanation:
During embryological development, the intermediate stages of one group of organisms exhibit stages of evolution in form of features of other groups. This suggests that the given group must have a common ancestor with the other group. It is called "ontogeny repeats phylogeny".
Example: Human embryo has a tail which otherwise is the feature of reptiles.
