How do hormones play a role in bodies of athletes?

Which of the following explains why a tree is often used as a model to represent the principle of common descent

The embryos of a bird, a reptile, and a mammal are similar in appearance. how does comparing the physical appearance of embryos of different species support the theory of evolution? a. it shows that these organisms share a common ancestor. b. it provides evidence that these organisms eat the same foods.c. it shows that these organisms share the same habitat.d. it provides evidence that these organisms suffered a genetic mutation.

20 the main source of energy for our planet comes from the