Each of the following paragraphs is incomplete. Choose the best sentence to make them complete. 选择合适的句子完成下面段落。Other animals, it is true, communicate with one another by means of cries: for example, many birds utter walling calls at the approach of danger; monkeys utter different cries, such as expressions of anger, fear and pleasure. ____ For instance, animals’ cries do not express thoughts and feelings clearly. This means basically, that they lack structure. They lack the kind of structure that enables us to divide a human utterance into words. We can change an utterance by replacing one word in it with another. A good illustration of this is a soldier who can say, e.g, “tanks approaching from the north”; but a bird has a single alarm cry, which means “danger!” This is why the number of signals that an animal can make is very limited: the great tit is a case in point; it has about twenty different calls. On the other hand, in human language the number of possible utterances is infinite. It also explains why animal cries are very general in meaning.
选项：

A:Furthermore, these various means of communication are very important for animals’ survival.
B:More importantly, these various means of communication contribute a lot to our understanding of human language.
C:However, these various means of communication differ in important ways from human language.