高中英语问题of the two sister,betty is___,and she is also the one

高中英语问题of the two sister,betty is___,and she is also the one who loves to be quiet
of the two sister,betty is___,and she is also the one who loves to be quiet
a a younger b a youngest c the youngest d the younger
选哪个?
john is one of these men who i am sure always do__best even under difficult conditions
his还是their?