(2013·皖南八校模拟)The band was very successful in the seventies, most of

　　　members were in their twenties.

A．its

B．whose

C．whom

D．which

一组数据的标准差，反映这组数据的（）。

A.分布范围

B.差异大小

C.取值水平

D.集中位置