单项选择题AUniversitycustomerhasaBladeCenterHfullypopulatedwithLS21Blades,asingleAMM,andfourpowermodules.TheBladeCenterhasbeenrunningflawlesslyforthreemonths.Onedayanadministratordiscoversthattheycannotviewvideoonblades9-12eitherlocallyorremotelyeventhoughtheystillappeartoberunning.Thevideoworksonalloftheotherblades.Whichofthefollowingisthecauseofthevideoproblem?()
A.A power module has failed and there is not enough power to see video on all blades.
B.MUX 3 on theBladeCenter backplane has failed.
C.A firmware update is required on the AMM.
D.A second AMM is required to view video on blades 9-14.