Why does the Yerkes-Dodson law describe performance during stressful situations as a bell-shaped (inverted-U) curve? Use the example of giving a high-stakes oral thesis defense to illustrate your explanation.

• A. Because performance steadily increases as arousal rises, so being more nervous during the defense always improves speaking and recall.
• B. Because performance is highest at very low arousal and declines as arousal increases, so being calm is always best.
• C. Because performance improves with moderate arousal (enhancing focus) but declines when arousal is too high (hurting memory and decision-making), with a lower optimal arousal for difficult tasks like a thesis defense.
• D. Because arousal and performance are unrelated and any observed bell shape is an artifact of measurement.