This is a tag question, and the rules are: If the main clause is positive, the tag is negative, and vice versa. The auxiliary (helping) verb used in the statement is repeated in the tag. The pronoun in the tag must agree with the subject. With these rules, the tag is meant to be "hadn't he". However, since this is not an option, the best answer to this question is: "Isn't it?" "Isn't it?" can be used informally to ask for agreement to the statement made, as in "Is that not so?"