Final answer:
Based on the given context, the action that Professor Plum performs towards Wadsworth in Scene 14 is most accurately described as threatening Wadsworth with a revolver.
Step-by-step explanation:
The student's question seems to ask for the correct action performed by Professor Plum based on a given passage from a play or narrative. The provided scenes all involve characters wielding a revolver, pointing it towards someone, or contemplating shooting. In the specific scene described, Professor Plum pulls out the revolver and points it at Wadsworth. Based on the context clues from the scenes, the action performed by Professor Plum in response to Wadsworth would most accurately be (c) Professor Plum threatens Wadsworth. This is because pulling out a revolver and pointing it at someone is commonly understood as a threatening gesture, rather than actually firing the weapon (a), denying it (b), or dismissing it (d).