TOEFL Reading: ETS-TOEFL阅读机经 - 364L34UAID8C76_1L$

According to paragraph 2, which of the following animal types is the most efficient swimmer? A. Animals that are well suited to swimming completely submerged B. Animals such as ducks and muskrat C. Animals that spend their time both on the surface of the water and completely underwater D. Animals that produce only a small bow wave