Read the information about dolphins and answer the question.
Dolphins are highly intelligent marine mammals. They live in oceans all over the world. They communicate with each other using a variety of clicks and whistles. Dolphins are known for their playful behavior and often swim alongside boats. They eat fish and squid.
Which of the following is true about dolphins?
A) They live in fresh water.
B) They are land animals.
C) They eat only plants.
D) They communicate with clicks and whistles.