_______ of water makes Death Valley a desert, but it is by no means devoid.

A．Lacking

B．Being lack

C．Because of lack

D．Lack

下列各项应采取的交配实验方法分别是（）

①鉴别一只白兔是否是纯合体

②鉴别一对相对性状的显性和隐性

③不断提高小麦抗病品种的纯度

A.杂交、测交、自交

B.测交、杂交、自交

C.杂交、自交、测交

D.自交、测交、杂交