Personally I think it is the sales manager, rather than the sales girls, to blame.
A. is
B. that is
C. are
D. who are
网友回答
A. is
(答案→)B. that is
C. are
D. who are
解析：rather than与the sales girls形成比较结构，去掉rather than the sales girl旧可以看出宾语从句实际上是一个强调句，被强调的部分是宾语从句中的主语the sales manager，后面的rather than the sales girls也对句子谓语动词形式的选择形成了一定的干扰。考虑到主谓一致的原则，应该选B。