Are the parents who let their child who is walk in the dark alone at night considerate?
A. young enough
B. too young to
C. not old enough to
D. so young
网友回答
A. young enough
B. too young to
C. not old enough to
(答案→)D. so young
解析：分析句子结构，who is so young 在句为修饰的定语,另有let sb.do sth.