Two pulleys are connected by a belt as shown in the drawing above. If pulley Q makes 300 evolutions per minute, how many revolutions per minute does pulley P make ？（）
(1)The length of the belt is 12π.
(2)The ratio of the radius of pulley P to the radius of pulley Q is 2 to 1.
A．条件(1)充分，但条件(2)不充分．
B．条件(2)充分，但条件(1)不充分．
C．条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分．
D．条件(1)充分，条件(2)也充分．
E．条件(1)和条件(2)单独都不充分，条件(1)和条件(2)联合起来也不充分．
