Of the nine student, the greatest number that can serve together on commission C is

Nine students—O, P, Q, R, S, T, U, V, and W—are the only student who can serve on three commissions designated A, B, and C, and each student must serve on exactly one of the commissions. Commission A must have exactly one more member than does commissionB. It is    
possible that there are no members of commission C Neither O nor P nor Q can serve on commission A. Neither R nor S nor T can serve on commission B. Neither U nor V nor W can serve on commission C.