A、Only animal tears are to be valued. B、Only animal tears can kill certain bacteria. C、Only humans cry for others. D、Only humans

Why do we cry? Can you imagine life without tears? Not only do tears keep your eyes lubricated, they also contain a substance that kills certain bacteria so they cannot infect your eyes. Give up your tears, and you will lose this on-the-spot defence. Nobody wants to give up the flood of extra tears you produce when you get something physical or chemical in your eyes. Tears are very good at washing this irritating stuff out. Another thing you could not do without your tears is cry from joy, anger or sadness. Humans are the only animals that produce tears in response to emotions, and most people say a good cry makes them feel better. Many scientists believe that crying somehow helps us cope with emotional situations. One of the tear researchers, Winfred, is trying to figure out how it happens. One possibility he says is that tears discharge certain chemicals from your body, chemicals that build up during stress. If Fred is right, what do you think will happen to people who restrain their tears? Boys, for instance, cry only about a quarter as often as girls once they reach teenage years, and we all cry a lot less than we did as babies. Could it be possibly that we face less stress? Maybe we found another way to deal with it, or maybe we just feel embarrassed.
Questions 12 to 15 are based on the passage you have just heard.
12. What is not the benefit of crying?
13. In terms of tears, what is the difference between humans and other animals?
14. What does the passage mean about boys and girls?
15. What’s the main idea of this passage?