**Core Concept**
The question tests the understanding of **nitrate pharmacokinetics**, specifically focusing on the aspect of **first-pass metabolism**. Nitrates are a class of vasodilators used primarily in the treatment of **angina pectoris**. First-pass metabolism refers to the process where a drug is significantly metabolized as it passes through the liver for the first time, reducing its systemic bioavailability.

**Why the Correct Answer is Right**
The correct answer is related to the property of not undergoing significant **hepatic first-pass metabolism**, which allows for its direct action without substantial loss of potency. This characteristic is crucial for the therapeutic efficacy of nitrates, as it ensures a more predictable and reliable clinical response.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does undergo significant first-pass metabolism.
**Option B:** Also incorrect as it is subject to first-pass effects, reducing its bioavailability.
**Option D:** This option is wrong due to its extensive metabolism during the first pass through the liver.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that **isosorbide dinitrate** is one such nitrate that undergoes significant first-pass metabolism, whereas **isosorbide mononitrate**, its active metabolite, does not. This distinction is critical for understanding the pharmacokinetics and pharmacodynamics of nitrates in clinical practice.

**Correct Answer:** D. Isosorbide mononitrate.