Helen is much more kind to her youngest child than to the others of course make the othe

问题补充：

Helen is much more kind to her youngest child than to the others, of course, make the others unhappy.

A. who

B. which

C. she

D. that

答案：

A. who

(答案→)B. which

C. she

D. that

解析：考查非限制性定语从句。句意“海伦对最小的儿子比其他人更友善，这当然，使得其他孩子不高兴。”which可以指代整个句子。故选B。