Mary was much kinder to Jack than she was to the others, , of course, made all the others upset.
A. who
B. that
C. what
D. which
网友回答
A. who
B. that
C. what
(答案→)D. which
解析：考查非限制性定语从句。Which指代前面一句话的内容，在定语从句中做主语。句意：玛丽最Jack要比对别人更好，这一点当然让别人难过了。That不能引导非限制性定语从句；what不能引导定语从句。Who的先行词必须是人。故D正确。