参考答案

正确答案：D
解析：细节题。文章第一段指出“The biological clock tells plants when to form. flowers and when the flowers should open．It tells insect when to leave the protective cocoon and fly away．And it tells animals when to eat，sleep and wake．It controls body temperature，．．．．”。这说明，生物钟控制动植物生理的许多方面。这与D符合。A和B不全面；文中没有提到C。