First heart sound corresponds to:
Mitral valve opening
Mitral valve closing
Aortic valve closing
None of the above
The first heart sound (S1) includes mitral and tricuspid valve closure. 

The First heart sound is associated with closure of the A-V Valves.
The Second heart sound Is associated with closure of the Aortic and Pulmonary Valves.
The Third heart sound occurs at the beginning of the middle third of diastole. Occasionally a weak, rumbling third heart sound is heard at the beginning of the middle third of diastole.  
Atrial contraction sound (Fourth heart sound). 

Reference: : Guyton and Hall Physiology page no  283,284