Select the option that can be used as a one-word substitute for the given group of words.
To frighten or threaten someone, usually in order to persuade the person to do something he or she does not wish to do

The action described—frightening or threatening someone to force them into an action—is defined as to Intimidate.
Compel means to force someone to do something, but it doesn't necessarily carry the primary context of using fear or threats in the same manner as intimidate.

Forceless and Authoritative are adjectives, whereas a verb is needed.