下面哪个调度会出现死锁( )
A.T1:R(X),T2:W(X),T2:W(Y),T3:W(Y),T1:W(Y),T1:Commit, T2:Commit, T3:Commit B.T1:R(X),T2:W(Y),T2:W(X),T3:W(Y),T1:W(Y), T1:Commit, T2:Commit, T3:Commit C.T1:R(A),T2:W(B),T1:R(A),T3:R(C),T2:W(C),T4:W(A),T3:W(B) D.T1:R(A),T2:W(B),T3:W(C),T1: Commit,T2:W(A), T2:Commit,T3:W(B), T3:Commit正确答案A
