請依下文回答第 31 題至第 35 題
          Humans may not be the only ones to use grammar and vocabulary to speak and communicate. Scientists believe dolphins also use words and sentences to speak to each other. We have known for a long time that dolphins can communicate. New research has found that this communication is similar to the conversations humans have.Scientists say the clicks, whistles and other sounds that dolphins make appear to be sentences that let the sea creatures send messages to each other. The dolphins use their language to identify themselves, have relations with other dolphins, and do things together. Scientists say that one day, we may be able to understand dolphin language and talk to dolphins.
           Researchers at the Karadag Nature Reserve in Crimea made the discovery that dolphins had their own language after recording two Black Sea bottlenose dolphins. The dolphins were named Yasha and Yana. The scientists noticed that one dolphin listened to what the other was saying and then replied. Lead researcher Dr. Vyacheslav Ryabov said, "This exchange resembles a conversation between two people." He added, "This language exhibits all the design features present in the human spoken language. This indicates a high level of intelligence and consciousness in dolphins." Dr. Ryabov said the dolphins' language is, "a highly developed spoken language, like the human language."
【題組】31 What is the best title for this passage?
(A) Dolphins Can Speak Human Languages.
(B) Yasha and Yana Have One-way Conversations.
(C) Sea Creatures Send Messages in the Same Way.
(D) Dolphin Language May Have Grammar.