Change in level is given by :
C = increase in level - decrease in level.
Now,
Decrease in level in March is 2 1/4 = 9/4 inches.
Increase in level in April is 1 5/8 = 13/8 inches.
Putting value of these in above equation, we get :
C = 13/8 - 9/4
C = 13/8 - 18/8
C = -5/8 inches
Therefore, the overall level after April will decrease by 5/8 inches.
Hence, option 4. is correct.
