Don't you know,my dear friend,()it is your money not you that she loves a.who b.which c.that d.w

Don't you know,my dear friend,()it is your money not you that she loves a.who b.which c.that d.w...

c.that
my dear friend是插入语，不干涉其他句子成分关系。因此，这是know的选择宾语从句的先行词that，而不能用定语从句的先行词 a.who b.which ，更不能用what。这个宾语从句已经有it这个形式主语，what会导致它的句子成分与it重叠。

my dear friend作插入语，可以先把它去掉，这样你就看得更清楚了。
Don't you know,()it is your money not you that she loves 很明显括号后的句子作know的宾语从句，中间用宾语从句连词that。本来可以省略，但因为中间用逗号隔开，所以必须用。