**Core Concept**
Chandani's presentation of chest pain not associated with exercise and multiple non-ejection clicks on auscultation suggests a condition affecting the heart valves, specifically the mitral valve. The mitral valve click is a characteristic finding in mitral valve prolapse (MVP), a condition where the mitral valve leaflets bulge back into the left atrium during systole.

**Why the Correct Answer is Right**
The diagnosis of mitral valve prolapse (MVP) can be confirmed using echocardiography, which allows for the visualization of the mitral valve leaflets and assessment of their function. In MVP, the echocardiogram may show a characteristic "sail-like" appearance of the mitral valve leaflets, with prolapse into the left atrium. Additionally, the echocardiogram can assess the degree of mitral regurgitation, which is often present in MVP.

**Why Each Wrong Option is Incorrect**
**Option A:** Chest X-ray is not a primary diagnostic tool for MVP, as it may show nonspecific findings such as cardiomegaly or pulmonary venous congestion.
**Option B:** ECG may show nonspecific findings such as T-wave inversion or ST-segment depression in patients with MVP, but it is not diagnostic.
**Option C:** Cardiac catheterization may be used to assess coronary artery disease or cardiac function, but it is not a primary diagnostic tool for MVP.

**Clinical Pearl / High-Yield Fact**
MVP is often associated with other conditions such as mitral regurgitation, atrial septal defects, and myxomatous degeneration of the mitral valve.

**Correct Answer:** C. Echocardiography.