GMAT Sentence Correction (SC) | I need to know who’s to blame for all the mistakes I found. (A) I need

Source: Nova GMAT

I need to know who’s to blame for all the mistakes I found.

(A) I need to know who’s to blame for all the mistakes I found.
(B) I need to know whose to blame for all the mistakes I found.
(C) I need to know who to blame for all the mistakes I found.
(D) I need to know who is to blame for the mistakes I found.
(E) I need to know whose’s to blame for all the mistakes I found.

---