My father has many books ,some of _____ are on history

My father has many books ,some of _____ are on history
I have many books,some of ____ are on chemistry.
A.them B that C.which D.those
选哪个?为什么?
为什么选择C .还不不懂.后面不是一个独立的句子吗?
麻烦具体分析一下句子结构.

为您解答如下：
C.which 为正确选项.
知识点延伸----------
1,some前面是个逗号,且没有连词,说明后半部分不是独立的分句,必须是修饰成分.填which,构成定语从句,修饰books.
2,some前面的逗号如果改为句号,则后半部分是个独立的句子,后半部分不是修饰成分.此时选A,them,同时some的首字母用大写S.
3,some前面加连词and,则也选A,them.此时,前后两部分构成并列句,不是修饰关系.
4,下列句子均为正确表达,意思一样,但表达方式不同.请楼主好好领会：
（1）My father has many books ,some of which are on history.
（2）My father has many books.Some of them are on history.
（3）My father has many books,and some of them are on history.
5,英语中的标点符号（尤其是逗号和句号）相当重要,它们决定着前后两部分是相互独立还是修饰与被修饰关系.