Subject: mathqa
Question: a closed cylindrical tank contains 36 pie cubic feet of water and its filled to half its capacity . when the tank is placed upright on its circular base on level ground , the height of water in the tank is 4 feet . when the tank is placed on its side on level ground , what is the height , in feet , of the surface of the water above the ground ?
Option: 
A: 3 feet', 'e ) 4 feet']
B: 2 feet', 'd ) 3 feet', 'e ) 4 feet']
C: 4 feet']
D: 1 feet', 'c ) 2 feet', 'd ) 3 feet', 'e ) 4 feet']
Answer: A