Language learning begins with.

Language learning begins with listening. Children are greatly different in the amount of listening they need before they start speaking, and children who start speaking late are often long listeners. Most children will “obey”spoken instructions some time before they can speak, though the word “obey” can hardly describe the cooperation(作) shown by the children. Before they can speak, many children will also ask questions by gestures(手势) and by * noises. 　It is agreed that babies enjoy * noises, and that during the first few months one or two special noises are used by them to show their happiness, pain, friendliness, and so on. But since these cannot be said to be a kind of communication, they can hardly be regarded as early forms of language. From about three months old they play with sounds for enjoyment, and by six months they are able to add new sounds to their store. This self-imitation(自我模仿) leads to deliberate(有意的）imitation of sounds made or words spoken to them
by other people. The problem then appears is that can these imitations be considered as speech? 　　It is a problem we need to get our teeth into(全身心做……). The meaning of a word depends on what a special person means by it in a special situation, and what a child means by a word will change as he gets more experience of the world. Playful and meaningless imitation of what other people say continues after the child has begun to speak for himself. I wonder, however, whether anything is gained when parents try to use this ability to teach new sounds. The problem that a baby's imitations can be considered as speech ________. A. is important because words h*e different meanings for different people B. is not especially important because the change takes place gradually C. is one that should be properly understood because the meaning of words changes with age D. is one that should be completely ignored (忽略) because children’s use of words is often meaningless 为什么这题选B 不选C 根据第四段的线索，感觉B C 都可以 麻烦老师帮忙解释下。
阅读理解中对句子的理解。