In 2000, the cost of p pounds of potatoes was d dollars. In 2010, the cost of 2p pounds of potatoes was \(\frac { 1 } { 2 } d\) dollars. By what percent did the price of potatoes decrease from 2000 to 2010?
(A)25\% (B)50\% (C)75\% (D)100\% (E)400\%
C