**Core Concept**
Aortic stenosis is a valvular heart disease characterized by the narrowing of the aortic valve opening, leading to obstruction of blood flow from the left ventricle to the aorta. This results in symptoms such as angina, syncope, and congestive heart failure due to increased pressure and resistance against which the left ventricle must pump.

**Why the Correct Answer is Right**
The correct answer is aortic stenosis. The triad of symptoms - angina, syncope, and congestive heart failure - is classic for aortic stenosis. The narrowing of the aortic valve opening leads to an increase in left ventricular pressure and a subsequent decrease in cardiac output, resulting in angina and syncope. As the disease progresses, the left ventricle becomes unable to pump efficiently, leading to congestive heart failure. The mechanism of aortic stenosis involves the calcification and fibrosis of the aortic valve leaflets, which can be due to age-related changes or other underlying conditions such as rheumatic heart disease.

**Why Each Wrong Option is Incorrect**
* **Option A:** Mitral stenosis typically presents with symptoms such as dyspnea, orthopnea, and paroxysmal nocturnal dyspnea, rather than the triad of angina, syncope, and congestive heart failure. Mitral stenosis involves the narrowing of the mitral valve opening, which can lead to left atrial enlargement and pulmonary congestion.
* **Option B:** Mitral regurgitation typically presents with symptoms such as dyspnea, fatigue, and palpitations, rather than the triad of angina, syncope, and congestive heart failure. Mitral regurgitation involves the leakage of blood from the left ventricle back into the left atrium during systole.
* **Option C:** Tricuspid regurgitation typically presents with symptoms such as jugular venous distension, edema, and hepatomegaly, rather than the triad of angina, syncope, and congestive heart failure. Tricuspid regurgitation involves the leakage of blood from the right ventricle back into the right atrium during systole.

**Clinical Pearl / High-Yield Fact**
The "classic" triad of symptoms for aortic stenosis is angina, syncope, and congestive heart failure. However, it's essential to note that not all patients with aortic stenosis will present with this triad, and some may have asymptomatic disease.

**Correct Answer: A. Aortic stenosis**