生生把羊拴在树桩上，要使羊最大吃草面积为314㎡，那栓羊绳应为______．

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．