关于定语从句.Thousands of people died in the Gulf Was,____children

题目

关于定语从句.Thousands of people died in the Gulf Was,____children
Thousands of people died in the Gulf Was,____children
A.many of whom were B.and many of whom were C.many whom were D.many are
老师给的答案是A 可是为什么不选B?不是前面有逗号么

答案

and 连接的是两个并列的句子,那么and后面应该是：and many of them were children