Who Vs. Whom

A) Whom is your closest friend?

B) Who is your closest friend?

A) Who do you bank with?

B) Whom do you bank with?

A) Who do you think will win the award?

B) Whom do you think will win the award?

A) Clare knows whom the winner is already.

B) Clare knows who the winner is already.

A) Whom was that in the clown costume?

B) Who was that in the clown costume?

A) Kathy was not sure who she was voting for.

B) Kathy was not sure whom she was voting for.