It is necessary that every school-age child in China----- sc

It is necessary that every school-age child in China_____ school.
A.attends B.attend C.will attend D.attended
中国所有适龄孩子都必须上学.
选B,
因为,孩子必须上学,选项省略了should ,完整的答案是should attend,情态动词,后面必须动词原形
句型：
it is 形容词that sb do sth