解析：问题中的关键词是adult dolphins和baby dolphins。对应原文第四段第一句，“We are building up a catalogue of the different whistle types they use and trying to associate them with behavior. like foraging，resting，socialising and the communications of groups with calves．”说科学家正在设法将啸声与海豚的行为特性联系起来，包括海豚觅食、休息、社交和有幼崽的群体间的交流等，由此可知这也包括成年海豚与小海豚之间的联络这种行为。题句的意思与原句的意思相符，所以答案是A。