Consider the following two transactions: (SHOW WORK)

T13: read(A); read(B);

if A = 1 then B := B - 1; write(B).

T14: read(B); read(A);

if B = 1 then A := A - 1;

write(A).

Let the consistency requirement be A = 1 or B = 1, with A = 1 and B = 1 as the initial values.
a. Show that every serial execution involving these two transactions preserves the consistency of the database.
b. Show a concurrent execution of T13 and T14 that produces a nonserializable schedule.
c. Is there a concurrent execution of T13 and T14 that produces a serializable schedule?