Which of the following schedules is (conflict) serializable? For each serializable schedule, determine the equivalent serial schedules.

a. r1(X); r3(X); w1(X); r2(X); w3(X);
b. r1(X); r3(X); w3(X); w1(X); r2(X);
c. r3(X); r2(X); w3(X); r1(X); w1(X);
d. r3(X); r2(X); r1(X); w3(X); w1(X);