**Core Concept**
Hyperrophic cardiomyopathy (HCM) is a genetic disorder characterized by thickening of the heart muscle, particularly the left ventricle, which can lead to impaired cardiac function and sudden cardiac death. It is a leading cause of sudden cardiac death in young athletes.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of HCM. In HCM, the thickened heart muscle can lead to a reduction in the left ventricular chamber size, which can result in a reduction in the left ventricular volume. This reduction in volume can lead to an increase in the left ventricular wall tension, which can cause a systolic murmur. The murmur is typically a harsh, mid-systolic click followed by a late systolic murmur.

**Why Each Wrong Option is Incorrect**
**Option A:** The presence of a loud systolic murmur is consistent with HCM, as it is a common finding in this condition. The murmur is often associated with the narrowing of the left ventricular outflow tract (LVOT) due to the thickened heart muscle.

**Option B:** The family history of sudden cardiac death is also consistent with HCM, as it is a genetic disorder that can cause sudden cardiac death in young individuals.

**Option C:** The presence of a loud systolic murmur and a family history of sudden cardiac death are both consistent with HCM. This option is also correct.

**Option D:** This option is incorrect because HCM is typically characterized by a reduced left ventricular volume, not an increased volume.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that HCM can be asymptomatic in its early stages, and the presence of a loud systolic murmur may be the only clue to its diagnosis. A thorough family history and a careful physical examination are crucial in identifying individuals at risk of HCM.

**Correct Answer:** D.