阅读下列短文, 从每题所给的四个选项(A、B、C和D) 中选出最佳选项。 Recently, researchers have found that dolphins know their com name s mu ch like people. Dolphins talk to one another with whistles(口哨) and calls. Scientists have known that the animals also use unusual whistles to name each other. They had thought that dolphins only heard each other's voices. However, the scientists didn't know that dolphins listen for their names too.
To test this idea, the researchers caught 14 dolphins and recorded their name calls. The scientists then copied earth dolphin's voice. Wren the changed recordings were played, the dolphins replied strongly to the names of their relatives and group members. They paid no attention to the names of dolphins they did not know.
Dolphins live in large groups that grow and change. Each dolphin's unusual whistle helps it quickly find a friend or a family member, or call for help. Understanding their calls requires learning. It's a skill that's seen in very few animals, which include humans and elephants.
Elephants, for example, communicate with sound. Their sounds can be heard by other elephants miles away. Dolphins, too, communicate with each other by making sounds like this. Elephants also communicate by moving their head, feet and trunk(象屏) . In much the same way. dolphins communicate by their movements. They often touch each other to express friendship.
Unlike dolphins, elephants also communicate by their great sense of smeИ. They can recognize other elephants by the smells they have.
Why do dolphins and elephants share the gift of communication? Scientists think it may be because they are social and smart animals. Both have st roag family relationship. Now, whether they also have nicknames(绰号) is another question!