题目内容：

有关高中定语从句的问题
In the bag he found a piece of paper ______some  special words.
A on which were written     B on that were written
all the apples __fell down were eaten by the pigs.
A which     B that
我已经排除了两个答案,选出正确答案后,请说明错误答案错在哪里,