why do a chicken embryo and a cow embryo look very similar even though the adults do not?\nthey are not…

Answer:

B. They are distantly related, so their development is similar.

Brief Explanations:

Chicken and cow are both vertebrates. According to the theory of evolution, they share a common ancestor in the distant past. Embryonic development often retains more ancestral traits compared to adult forms. So, their similar embryonic appearance is due to their distant evolutionary relationship. Option A is wrong as they are related (both vertebrates). Option C is incorrect as it's not about mutation in utero in this context. Option D is wrong as the genetic makeup of the species doesn't change during development in this sense (genetic variation occurs through other mechanisms like mutation over generations, not during normal embryonic development of an individual).