Question

question
the first heart sound (lub) results from closing the _ valves.
answer
tricuspid and pulmonary semilunar
biscuspid (mitral) and aortic semilunar
tricuspid and biscuspid (mitral)
pulmonary and aortic semilunar
i dont know yet

Explanation:

The first heart sound (lub) occurs when the atrioventricular (AV) valves close. The AV valves are the tricuspid (between right atrium and right ventricle) and bicuspid (mitral, between left atrium and left ventricle) valves. The semilunar valves (pulmonary and aortic) closing cause the second heart sound (dub).

Answer:

tricuspid and bicuspid (mitral)