You cannot forbid him leaving.

The correct answer is: C. him to leave

The sentence "You cannot forbid him leaving" is grammatically incorrect. The correct way to say this is "You cannot forbid him to leave."

The reason for this is that the verb "forbid" takes a direct object, which is the person or thing that is being forbidden. In this case, the direct object is "him." The verb "to leave" is an infinitive, which is a verb form that is used to express purpose or intention.

Here are some other examples of how to use the verb "forbid":

• The teacher forbade the students from talking in class.
• The parents forbade their children from watching TV after 9pm.
• The judge forbade the defendant from contacting the victim.

I hope this helps!