A right circular cylinder, open at the top, is filled with a liquid of specific gravity 1.2, and rotated about its vertical axis at such a speed that half of the liquid spills out. The pressure at the centre of the bottom is
(A) Zero
(B) one-fourth its value when the cylinder was full
(C) one-third its value when the cylinder was full
(D) three-fourth its value when the cylinder was full