Acow and a frog have similar bone structures in their forelimbs. both have phalanges, radius, ulna, and humerus bones. however, the cow and frog are animals with very different life cycles from each other. which most likely describes why the body structures of these animals are so similar? a. both have undergone similar mutations. b. both descended from a common ancestor. c. both reacted similarly to environmental pressures. d. both spread out from the same geographical region

The answer maybe B)Both descended from a common ancestor.

Reason: Since the cow and frog has similar bone structures, they probably had a common ancestor that used these structures to survive. For example, the common ancestor probably had hands or feet and used them to fight, gather food, walk, etc. Overtime, the common ancestor's offspring may have evolved in to new species who use these bone structures to evolve into feet, hands, or even fins.
     They evolved in to these new things to better suit there environment just like how a deep sea fish may glow to help them see or how a zebra's skin is striped to fool predators that can't see well. These changes help organism adapt o their environment.

(I hope this helps)

Number one is sinkholes may form from water erosion