Language as a System of Symbols Of all systems of symbols , language is the most highly developed. It has been pointed out that human beings, by agreement, can make anything stand for anything. Human beings have agreed, in the course of centuries of mutual  dependency, to let the various noises that they can produce with their lungs, throats, tongues, teeth, and lips systematically stand for certain happenings in their nervous systems. We call that system of agreements language. There is no necessary connection between the symbol and that which it stands for. Just as social positions can be symbolized by feathers worn on the head, by gold on the watch chain, or by a thousand other things according to the culture we live in, so the fact of being hungry can be symbolized by a thousand different noises according to the culture we live in. However obvious these facts may appear at first glance, they are actually not so obvious as they seem except when we  _ to think about the subject. Symbols and the things they stand for are independent of each other, yet we all have a way of feeling as if, and sometimes acting as if, there were necessary connections. For example, there are people who feel that foreign languages are unreasonable by nature: foreigners have such funny names for things, and why can't they call things by their right names? This feeling exhibits itself most strongly in those English and American tourists who seem to believe that they can make the natives of any country understand English if they shout loud enough. Like the little boy who is reported to have said: "Pigs are called pigs because they are such dirty animals," they feel the symbol is inherently  connected in some way with the things symbolized. Language is a highly developed system of symbols because human beings   _  .
have made use of language for centuries use our nervous systems to support language have made various noises stand for any events can make anything stand for anything by agreement
Question: Language as a System of Symbols Of all systems of symbols , language is the most highly developed. It has been pointed out that human beings, by agreement, can make anything stand for anything. Human beings have agreed, in the course of centuries of mutual  dependency, to let the various noises that they can produce with their lungs, throats, tongues, teeth, and lips systematically stand for certain happenings in their nervous systems. We call that system of agreements language. There is no necessary connection between the symbol and that which it stands for. Just as social positions can be symbolized by feathers worn on the head, by gold on the watch chain, or by a thousand other things according to the culture we live in, so the fact of being hungry can be symbolized by a thousand different noises according to the culture we live in. However obvious these facts may appear at first glance, they are actually not so obvious as they seem except when we  _ to think about the subject. Symbols and the things they stand for are independent of each other, yet we all have a way of feeling as if, and sometimes acting as if, there were necessary connections. For example, there are people who feel that foreign languages are unreasonable by nature: foreigners have such funny names for things, and why can't they call things by their right names? This feeling exhibits itself most strongly in those English and American tourists who seem to believe that they can make the natives of any country understand English if they shout loud enough. Like the little boy who is reported to have said: "Pigs are called pigs because they are such dirty animals," they feel the symbol is inherently  connected in some way with the things symbolized. Language is a highly developed system of symbols because human beings   _  .
A. have made use of language for centuries
B. use our nervous systems to support language
C. have made various noises stand for any events
D. can make anything stand for anything by agreement
Answer: