Which of the following schedule is recoverable ?

Описание: Consider the following schedules:
S1: r1(X); w1(X); r1(Y); w1(Y); r2(X); w2(X); C2; C1;
S2: r1(X); w1(X); r2(X); r1(Y); w2(X); w1(Y); C1; C2;
Which of the following is true?

(A) Both S1 and S2 are recoverable
(B) S1 is recoverable, but S2 is not
(C) S2 is recoverable, but S1 is not
(D) Both schedules are non recoverable

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