The coastguards came out to help the author becauseA．they discovered the author capsized h

The coastguards came out to help the author because

A．they discovered the author capsized his catamaran.

B．the author encountered a big whale.

C．they had lifesaving obligation.

D．they were well-meaning people.

请帮忙给出正确答案和分析，谢谢！