Read this passage about seals and sea lions and then answer the question that follows: From a distance, they both look like seals, but once you get up close you can actually see the difference. Seals and sea lions are both fish-loving mammals. Moreover, handy flippers propel them both through the water. But while seals have a tiny opening on the side of their heads, sea lions have actual earflaps. Furthermore, sea lions use their back flippers like feet to scoot along the beach. On the other hand, seals must wriggle and roll to get ahead. On the whole, when you visit a zoo or theme park, it's the honking, barking, funny sea lion you're likely to find playing to the crowds for fishy treats, earflaps and all.

In the passage about seals and sea lions, what is the purpose of the transition on the whole?

A. To show a contrast
B. To show a comparison
C. To emphasize an idea
D. To summarize