To thwart is to:

• A. Weaken
• B. Make fun of
• C. Oppose
• D. Threaten

Answer: (C)

Thwart means to stop someone from achieving a goal by opposing or obstructing their plan. That makes The best fit is oppose, because to oppose is to stand against someone’s efforts and hinder their progress, which directly captures the idea of preventing a plan from succeeding. The other options miss that core action: weaken describes reducing strength but not necessarily preventing the outcome; making fun of is mocking and has no direct impact on whether a goal is achieved; threaten involves intimidation, which is a different approach and not the defining sense of thwart. For example, thwarting a plan means blocking its steps so it can’t succeed, often by actively opposing or obstructing it.