Consider the following two transactions:

• T1: R(C); R(A); W(B); R(D);
• T2: R(B); R(D); W(A); R(C);

Which of the listed schedules is compatible with the 2PL protocol.

• R1(C); R1(A); R2(B); R2(D); W1(B); W2(A); R1(D); R2(C); C1; C2
• R1(C); R1(A); R2(B); R2(D); W2(A); W1(B); R1(D); R2(C); C2; C1
• R2(B); R2(D); R1(C); W2(A); R1(A); R2(C); W1(B); R1(D); C1; C2
• R1(C); R1(A); W1(B); R1(D); C1; R2(B); R2(D); W2(A); R2(C); C2