Rianna is writing an informational article about bottlenose dolphins. She wants to add one more supporting idea to the following paragraph: Bottlenose dolphins are very social animals. They travel in pods typically made up of 2 to 15 dolphins. In these pods, they communicate with one another by means of an intricate system of whistles and squeaks. They band together for the purposes of hunting, mating, and defending themselves from predators. Which of the sentences below is a supporting idea for the central idea of this paragraph? A. Dolphins have a varied diet; they eat bottom-dwelling fish, shrimp, and squid. B. Dolphins are mammals and thus have to surface above the water in order to breathe. C. Dolphin pods will rally around an injured dolphin, helping it surface to breathe if it cannot swim on its own. D. Dolphins always seem to be smiling, thanks to their curved mouths, and people often think of them as very friendly.