Essential research study related to New invention mostly useful for human being with helping modern world
A. knew, because if you think about how they all sound, B and C could not work, since they sound kind of weird. D sound like it could work, but only if it was "had <em>know</em><em>n</em>". Therefore the only answer left to pick is "A. knew".
The sentence that the pronoun comes before the antecedent is: His reputation was Tom's greatest possession. The correct answer is option C. The pronoun used in the sentence is "His" and the antecedent referred by the pronoun "his" is the noun "Tom".
