题目

Green is an important color in nature. It is the color of grass and the leaves on trees. It is the color of most growing plants, too. Sometimes, the word green means young, fresh and growing. Sometimes, it describes something that is not yet finished or plants that are not ripe. For example, a greenhorn is someone who has no experience, who is new to a situation. In the fifteenth century, a greenhorn was a young cow or ox whose horns had not yet developed. A century or so later, a greenhorn was a soldier who had not yet had any experience in war. By the eighteenth century, a greenhorn 14．若函数f（x）=x3-3ax+1在区间（0，1）内有极小值，则a的取值范围是（　　）A．（0，1）B．（0，1]C．[0，1）D．[0，1]