State which of the following schedules are serializable.

a. r1(x) r2(y) r1(z ) r3(z ) r2(x) r1(y)
b. r1(x) w2(y) r1(z ) r3(z ) w2(x) r1(y)
c. r1(x) w2(y) r1(z ) r3(z ) w1(x) r2(y)
d. r1(x) r2(y) r1(z ) r3(z ) w1(x) w2(y)
e. w1(x) r2(y) r1(z ) r3(z ) r1(x) w2(y)

a. Yes. all transactions just read.
b. No. Transaction T1 is before Transaction T2 on x and after Transaction T2 on y.
c. Yes. Transaction T1 and Transaction T2 write and read different variables.
d. Yes. Transaction T1 and Transaction T2 write and read different variables.
e. Yes. Transaction T1 and Transaction T2 write and read different variables.