单选题 Sooner or later the forests will disappear unless ______.

A、 every country has a plentiful supply of trees
B、 every government has a good education system
C、 all the people realize how important it is to keep a plentiful supply of trees
D、 every government realizes the importance of trees services

【正确答案】 C

【答案解析】此题可从第四段小结得出。只有人类认识到树木对人类生存环境起着重大的作用，才能自觉地保护好我们的地球。