the image above shows an inverted U-tube with the open end, O of one limb below the level, W of water in the tank, in order that water should begin to flow from the tank it is is necessary that
A.
The U-tube is completely filled with water and that P should be higher that W
B.
P should be lower than O and W
C.
P should be lower than W and O should reach the bottom of the table
D.
The U-tube is completely filled with water and that P should be lower that W
Correct answer is B
No explanation has been provided for this answer.