Question: A cow 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?

What is the correct answer to the question from the following choices?
Available choices:
[i] Both have undergone similar mutations.
[ii] Both descended from a common ancestor.
[iii] Both reacted similarly to environmental pressures.
[iv] Both spread out from the same geographical region.
[ii]