单项选择题
WhatisthepurposeoftheWLCController－>Multicast－>IGMPTimeoutfeatureoperatingonv5.2?（）
A.todetermineiftherearemoreclientsthatareusingthemulticaststream
B.tolimitthetimethataclienthastorequestanIGMPjointothecontrollermulticastgroup
C.todetermineifthemulticastrouterisstillaliveandrespondingtomulticastclients
D.toremoveclientsfromthemulticastgroupifthemulticasttrafficexceedstheallottedbandwidthallowed