Sentence Correction

Ques: No one but him could have told them that the thief was I.

A) him could have told them that the thief was I.
B) he could have told them that the thief was I.
C) he could have told them that the thief was me.
D) him could have told them that the thief was me.
E) he could have told them the thief was me.

Can anybody help me on this? What is the correct answer and why?

Thanks

Is it {C}??

Is it {C}??