Answer: D. Thinning of the valve flaps.
Explanation:
A valve is a structure inside a mammalian heart which allows the flow of the blood in uni-direction.
The thinning of the valve flaps is not an age related change affecting the heart. In this condition the valve flaps become thin and leakage of blood may takes place through these flaps. The flaps are the leaflet like structures of the ventricle. Normally the valves have three flaps but the mitral valve has 2 flaps. This is a possible cause of valvular degeneration. This happens commonly to mitral valve. This condition affects 4-5 percent of the total world population.
