**Core Concept:** A second heart sound, also known as the S2, is the result of the closure of the mitral and tricuspid valves, which occur during ventricular systole. The first heart sound (S1) is due to the closure of the aortic and pulmonary valves during diastole.

**Why the Correct Answer is Right:** The correct answer, option D (Mitral and Tricuspid Valves), is right because these valves are responsible for producing the second heart sound (S2) during ventricular systole. The mitral valve is located between the left atrium and left ventricle, and the tricuspid valve is between the right atrium and right ventricle.

**Why Each Wrong Option is Incorrect:**

A. The pulmonary valve (located between the right ventricle and pulmonary artery) and the aortic valve (located between the left ventricle and aorta) are responsible for producing the first heart sound (S1) during diastole, not the second heart sound.

B. The atrioventricular valves (mitral and tricuspid) are involved in producing S2, not the semilunar valves (pulmonary and aortic).

C. The bicuspid valve (also known as the aortic valve) is responsible for producing the first heart sound (S1), not the second heart sound (S2).

**Clinical Pearl:** The second heart sound (S2) is a crucial sign to identify in cardiac auscultation, as it provides information about ventricular function, chamber size, and valvular health. A normal S2 is a single, sharp sound, with a split S2 indicating the presence of a heart murmur, which may be indicative of valvular disease or other cardiac abnormalities.

**Correct Answer:** D. Mitral and Tricuspid Valves