Question

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

Explanation:

The first heart sound (lub) is produced by the closure of the atrioventricular valves. The atrioventricular valves are the tricuspid (between the right atrium and right ventricle) and bicuspid (mitral, between the left atrium and left ventricle) valves. The semilunar valves (pulmonary and aortic) closure causes the second heart sound (dub).

Answer:

tricuspid and bicuspid (mitral)