**Core Concept**
Amyl nitrate is a vasodilator used to treat angina pectoris. It works by releasing nitric oxide, which activates guanylate cyclase, leading to smooth muscle relaxation and vasodilation.

**Why the Correct Answer is Right**
Amyl nitrate is most commonly administered via inhalation. When inhaled, it rapidly releases nitric oxide, which diffuses into the bloodstream and activates guanylate cyclase, causing smooth muscle relaxation in the coronary arteries and peripheral vasculature. This leads to a decrease in blood pressure and an increase in coronary blood flow, providing symptomatic relief in angina pectoris.

**Why Each Wrong Option is Incorrect**
**Option A:** Sublingual administration is not the primary route for amyl nitrate.
**Option B:** Intravenous administration is not commonly used due to the risk of hypotension and reflex tachycardia.
**Option C:** Intramuscular administration is not the preferred route due to variable absorption rates and potential for systemic toxicity.

**Clinical Pearl / High-Yield Fact**
Amyl nitrate is a classic example of a vasodilator that works through the release of nitric oxide, which activates guanylate cyclase and leads to smooth muscle relaxation.

**Correct Answer: D. Inhalation**