**Core Concept**
A cheese reaction, also known as a tyramine reaction, occurs due to the ingestion of tyramine-rich foods, such as aged cheese, wine, and fermented meats, in patients taking monoamine oxidase inhibitors (MAOIs). This reaction is caused by the inhibition of monoamine oxidase, an enzyme responsible for breaking down tyramine, leading to a sudden and potentially life-threatening increase in blood pressure.

**Why the Correct Answer is Right**
The drug of choice for treating a cheese reaction is phentolamine, a non-selective alpha-adrenergic receptor antagonist. Phentolamine works by blocking the action of norepinephrine and epinephrine on alpha-adrenergic receptors, thereby reducing the blood pressure. This is crucial in managing the sudden increase in blood pressure caused by the cheese reaction.

**Why Each Wrong Option is Incorrect**
**Option A:** Norepinephrine is incorrect because it acts as a potent vasoconstrictor, which would further increase blood pressure in a cheese reaction.
**Option B:** Metoprolol is incorrect because it is a beta-blocker that can worsen the situation by blocking the beta-2 receptors, leading to unopposed alpha-receptor-mediated vasoconstriction.
**Option C:** Nitroglycerin is incorrect because it is a vasodilator that can further decrease blood pressure, which may be too low in a cheese reaction.

**Clinical Pearl / High-Yield Fact**
In patients taking MAOIs, it is essential to avoid tyramine-rich foods to prevent a cheese reaction. A memorable way to recall this is the "cheese- wine- beer" rule, where patients should avoid these foods and drinks while taking MAOIs.

**Correct Answer:** D. Phentolamine