海伦和辛迪是姐妹俩，姐姐有一头金色直发，而妹妹是栗色卷发。下列说法错误的是（）。

A头发的颜色是由基因控制的    B控制发色的基因成对存在

C她们发色的基因组成不同      D她们头发的细胞核内有23条染色体

Although students are ________ to more, they typically know less and are less mature than the

generations before.

[ ]

A. displayed

B. released

C. explored

D. exposed