若函数f（x）=ax³-3ax的递减区间为（-1，1），则a的取值范围为（　　）

A．a＞0

B．a＜0

C．-1＜a＜0

D．0＜a＜1

A survey shows that kid in UK are the unhappiest, though it is among the richest countries in the world.

_______, lot of money doesn't mean a happy childhood. [ ]

A. That is to say

B. As a result

C. For example

D. Above all