B. "Who" and "whom" are personal
pronouns.
Personal pronouns are pronouns that pertains to a number of
persons, the person, sex and the situation. For example, he is a boy. He is a
personal pronoun. Who is a subject pronoun but never a personal pronouns since
it doesn’t denote to a particular person, gender, event or case. Whom is object
pronoun used to answer him, her and us but also doesn’t refer to a definite
pronoun like the former, who.
