A:
Your sentences are the same.
Normal and natural: Who are you referring to?
Right: Whom are you referring to?
Right: To whom are you referring?
- Wrong: To who are you referring? (If you use "to" at the beginning you must use "whom"; you can't say "to who".)
- Wrong: To whom are you referring to? (You can't use "to" twice.)
- Wrong: To who are you referring to? (You can't use "to" at the beginning and at the end.)
Who versus Whom
“Who” (and “whoever”) is the subject case, and “whom” (and “whomever”) is the object case.
The subject case means I, he, she, it, we, you, they, who.
The object case means me, him, her, it, us, you, them, whom.
For example:
– *Who* is going to the party? *He* is going to the party.
– *Whom* is he going to the party with? He is going to the party with *her*.
– The doctor *who* called you yesterday is here to see you. (The doctor called you. *He* called you. The doctor *who* called you.)
– The doctor, *whom* you called yesterday, is here to see you. (You called the doctor. You called *him*. The doctor *whom* you called.)
HOWEVER
The word “whom” is disappearing from English. It sounds normal to say “who” for both the subject and the object.
– Who is going to the party? He is going to the party.
– Who is he going to the party with? He is going to the party with her.
– The doctor who called you yesterday is here to see you. (The doctor called you.)
– The doctor, who you called yesterday, is here to see you. (You called the doctor.)
But you MUST use “whom” after a preposition.
– *With whom* is he going to the party? He is going to the party *with her*.
– The doctor *with whom* you spoke yesterday is on the phone. He wants to talk to you.
about whom, at whom, by whom, for whom, from whom, of whom, to whom, with whom, etc.