The correct response is:
B - Their embryos share features in the early stages of development.
Explanation:
The evidence that supports the theory that fish and mammals evolved from a common ancestor is found in embryonic development. In the early stages of development, the embryos of both fish and mammals exhibit similar structures, such as pharyngeal arches and a notochord. These similarities indicate a common evolutionary origin, suggesting that both groups share a distant ancestor.
The other options do not provide as strong evidence for a common ancestor:
- A (their embryos share features in the late stages of development) is less relevant because the differences in development become more pronounced later on.
- C (they both produce egg and sperm cells that must join in fertilization) and D (they both emerge from fertilized eggs) describe general reproductive strategies common to many animals and do not specifically indicate a shared evolutionary lineage between fish and mammals.
Thus, option B is the strongest support for the idea that they evolved from a common ancestor based on embryonic similarities observed in early development.