Let T1, T2, and T3, be transactions that operate on the same database items, A, B, and C. Let r1(A) mean that T1 reads A, w1(A) mean that T1 writes A, and so on for T2 and T3. Each of the following shows the order of the reads and writes in a schedule for T1, T2, and T3. in each case, draw a precedence graph with nodes for T1, T2, and T3 and draw edges for conflicts. Determine if each schedule is serializable by examining the precedence graph. if it's serializable, give an equivalent serial schedule.

a. r1(A); r2(A); w1(A); r3(A); w3(A); w2(A);

b. r1(A); r1(B); r2(A); r3(B); r3(C); w2(A): w2(B);

c. r1(A); r3(C); r2(C); w3(A); r2(B); r3(B); w2(B); w2(A);

thank you in advance