**Core Concept**
Nitroglycerine is a vasodilatory medication used to treat angina pectoris. It works by releasing nitric oxide, which relaxes vascular smooth muscle and leads to vasodilation. This effect decreases the workload on the heart and improves oxygen supply to the myocardium.

**Why the Correct Answer is Right**
Nitroglycerine can be administered via various routes to achieve its therapeutic effect. Topical application, sublingual administration, buccal administration, and even inhalation are all effective methods. The medication is rapidly absorbed through mucous membranes or skin, allowing for quick onset of action. This flexibility in administration routes is beneficial for managing acute angina symptoms.

**Why Each Wrong Option is Incorrect**
**Option A:** There is no evidence to suggest that nitroglycerine is not effective when administered orally. In fact, oral sustained-release formulations are available for long-term management of angina.

**Option B:** Sublingual and buccal administration are common routes for nitroglycerine, allowing for rapid absorption and quick relief from angina symptoms.

**Option C:** Inhalation of nitroglycerine is also a viable option, particularly in patients with severe angina or those who cannot tolerate other routes.

**Clinical Pearl / High-Yield Fact**
Nitroglycerine's mechanism of action is primarily through the release of nitric oxide, which activates guanylyl cyclase and increases cyclic guanosine monophosphate (cGMP) levels in vascular smooth muscle cells. This leads to smooth muscle relaxation and vasodilation.

**Correct Answer:** D.