(6)设全集U={a,b,C),集合M={a},P={a,b},则下列表示空集的是 ( )
A、(<img src="//wximg.233.com/attached/image/20120915/20120915144216301630.gif" alt="" />UM)∩P
B、M∩ P
C、M∩(<img src="//wximg.233.com/attached/image/20120915/20120915144279297929.gif" alt="" />UP)
D、(<img src="//wximg.233.com/attached/image/20120915/20120915144322112211.gif" alt="" />UM)∩(<img src="//wximg.233.com/attached/image/20120915/20120915144381458145.gif" alt="" />UP)