In an exam a teacher has put the following example to fill in the gap:
Amici Rufi ____ noscebant.
According to the docent, if the right word has been selected, the translation in English should be:
The friends of Rufus knew him.
So, in my opinion the only possible option for filling the gap would be EUM since it corresponds to the function of him in the transaltion. An accusative, third person, singular, masculine pronoun. Could there be another option than this?