Of the two sisters,Lucy is one,and she is also the one who loves to be quiet.

问题描述:

Of the two sisters,Lucy is one,and she is also the one who loves to be quiet.
A.a younger B.a youngest C.the younger D.the youngest
为什呢选C 不选 D 呢

C 两者比较,the +比较级指两者中较.
希望可以帮到你!