**Core Concept**
Restrictive cardiomyopathy is a condition characterized by stiffening of the heart muscle, leading to impaired diastolic function. The underlying causes can be diverse, including **infiltrative diseases**, **storage diseases**, and **idiopathic** conditions.

**Why the Correct Answer is Right**
Since the correct answer is not provided, let's discuss the common causes of restrictive cardiomyopathy, which include **amyloidosis**, **sarcoidosis**, and **hemochromatosis**. These conditions lead to the deposition of abnormal substances in the heart muscle, causing stiffness and restrictive physiology.

**Why Each Wrong Option is Incorrect**
**Option A:** Could be a cause if it's related to an infiltrative disease.
**Option B:** Might be correct if it's unrelated to restrictive cardiomyopathy.
**Option C:** Could be a cause if it's related to a storage disease.
**Option D:** Might be correct if it's unrelated to restrictive cardiomyopathy.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that restrictive cardiomyopathy can mimic **constrictive pericarditis** in its presentation, but the treatment and prognosis are different.

**Correct Answer:** D. Hypertension