----you don't like him is none of my business.

A.That
That 引导的主语从句.
1.that引导的主语从句
that引导的主语从句既可以放在句首也可以放在句末,在实际应用中我们常常采用it形式主语的形式.
例句：That he passed the English test is true.千真万确,他通过了英语考试.
→It is true that he passed the English test.