Over two thirds of the population were believed to have no ______ to the health care in the west rural area in China.

A．aid

B．basis

C．belief

D．access

下列关于极重度精神发育迟滞的说法中正确的是()

A．智商水平低于20

B．成年以后可达到的心理年龄在3岁以下

C．不认识亲人及周围环境，对危险尚知躲避

D．大小便失禁

E．常合并严重脑部损害