a. Suppose schedule S, is defined as follows. [8] Sa reada(M ); write,(M ):read2(X); read (M); reada(Y);read (Z ):write,(Z );reada(Z )write(Y );reada(Y): read (M ):write2(M); Where, data items: X,YZ.M; read (X) means read operation performed on data item X by Transaction i; write,(X) means write operation performed on data item X by Transaction i; Is S, (conflict) serializable? Justify your answer. b. "Shadow paging technique can be categorized as UNDO/REDO technique for recovery." Is the statement correct? Justify. [4]