Which organism in a food chain is probably responsible for keeping the food web and the pyramids in their respective shapes? why?

Plz ! ive been stuck on this forever

Use the distance formula to determine weather each pair of segments have the same length

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.