**Core Concept**
Pulmonary vascular resistance (PVR) is a critical parameter in patients with heart failure, reflecting the pressure and resistance to blood flow in the pulmonary circulation. Elevated PVR is associated with increased morbidity and mortality in these patients. Accurate measurement of PVR is essential for guiding treatment decisions.

**Why the Correct Answer is Right**
N-terminal pro-b-type natriuretic peptide (NT-proBNP) has been shown to correlate well with pulmonary vascular resistance in patients with heart failure. Elevated levels of NT-proBNP are indicative of increased ventricular wall stress, which is also associated with increased PVR. This biomarker is a useful surrogate marker for assessing PVR in clinical practice.

**Why Each Wrong Option is Incorrect**
* **Option A:** B-type natriuretic peptide (BNP) is also elevated in heart failure, but it does not correlate as well with PVR as NT-proBNP.
* **Option B:** C-reactive protein (CRP) is a marker of inflammation, which is not directly related to PVR in heart failure patients.
* **Option C:** Troponin is a marker of cardiac injury, but it does not correlate with PVR in patients with heart failure.

**Clinical Pearl / High-Yield Fact**
Remember that NT-proBNP levels can help estimate PVR in heart failure patients, but they should not replace direct measurement of PVR, which is typically done using right heart catheterization.

**Correct Answer: C. Troponin is a marker of cardiac injury, but it does not correlate with PVR in patients with heart failure.**