The correct answer is: B. him
The pronoun “him” is used to refer to a male person. In the sentence “No, I have never met him,” the speaker is saying that they have never met a male person.
The pronoun “it” is used to refer to inanimate objects. In the sentence “No, I have never met it,” the speaker could be saying that they have never met a robot, a computer, or a car.
The pronoun “them” is used to refer to two or more people or things. In the sentence “No, I have never met them,” the speaker could be saying that they have never met two or more people, or that they have never met a group of people.
The pronoun “her” is used to refer to a female person. In the sentence “No, I have never met her,” the speaker is saying that they have never met a female person.
In this case, the speaker is most likely saying that they have never met a male person.