Not that I'm unwilling to go with you, ________I'm busy now.

Not that I'm unwilling to go with you, ________I'm busy now.

A.because

B.but

C.but that

D.however

答案及解析： C

解析：

not that... but that相当于 (It is) not because... but because...，意为"不是因为……而是因为……"。