Read the following passage and decide which answer (A, B, C or D) best fits each gap.     

       The ability to weep is a uniquely human form of emotional response. Some scientists have suggested that human tears are (51)_______ of an aquatic past – but this does not seem very likely. We cry from the moment we enter this world, for a number of reasons. Helpless babies cry to persuade their parents that they are ill, hungry or uncomfortable. As they (52)_______, they will also cry just to attract parental attention and will often stop when they get it. The idea that having a good cry do you (53)_______ is a very old one and now it has scientific validity since recent research into tears has shown that they (54)_______ a natural painkiller called enkaphalin. By fighting sorrow and pain this chemical helps you feel better. Weeping can increase the quantities of enkaphalin you (55)_______. Unfortunately, in our society we impose restrictions upon this naturally (56)_______ activity. Because some people still regard it as a (57)_______ of weakness in men, boys in particular are admonished when they cry. This kind of repression can only increase stress, both emotionally and physically. Tears of emotion also help the body (58)_______ itself of toxic chemical waste, for there is more protein in them than in tears resulting from cold winds or other irritants. Crying comforts, calms and can be very enjoyable – (59)_______ the popularity of highly emotional films which are commonly (60)_______ “weepies”. It seems that people enjoy crying together almost as much as laughing together.

Some scientists have suggested that human tears are (51)_______ of an aquatic past – but this does not seem very likely.