Here's why:
* Noun: It refers to a specific type of conflict, namely one that occurs within a person's mind or heart.
* Phrase: It's a group of words acting together as a single unit, describing a specific concept.
While "internal conflict" can be used in a sentence as the object of a verb (e.g., "The protagonist struggled with internal conflict"), it is not a verb itself.
To illustrate:
* Internal conflict: The psychological struggle within a character.
* Verb: "struggled" - indicates an action.