I had almost the same question on one of my quizzes but it had one other answer. Mine was,
"The picture below shows the bone structures of whale and bird.
Picture shows similar bone structures of whale and bird.
Based on the diagram, which of these statements is correct about whales and birds?
a ) They have similar food habits.
b ) They move in the same manner.
c ) They share a common ancestor.
d ) They use their limbs to catch their prey."
After doing some research, I found that the correct answer was that they share a common ancestor.