听下面一段独白，回答以下小题。
【小题1】

A．Because they have true blue eyes.

B．Because they look true blue underwater.

C．Because they have true blue underbellies.

D．Because they look true blue on the surface.

【小题2】

A．By giving out yellowish light.

B．By changing the color of their backs.

C．By emitting a series of pulses and sounds.

D．By traveling through the ocean at 20 miles an hour.

【小题3】

A．When they are angry, they let out the loudest noise.

B．They are highly intelligent animals without social life.

C．An ordinary-sized whale weighs as much as an elephant.

D．They rely on excellent hearing to communicate and navigate.