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Consider the following schedule 

$\text{S : r2(A), w1(B), w1(C), R3(B), r2(B), r1(A), commit_1, r2(C), commit_2, w3(A), commit_3 }$

Consider the following statements : 
S1 : Schedule(S) is conflict serializable schedule. 
S2 : Schedule(S) is allowed by 2PL. 
S3 : Schedule(S) is strict recoverable schedule. 
S4 : Schedule(S) is allowed by strict 2PL. 
How many above statements true about schedule(S) ?

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S1 is true as there is no cycle in the precedence graph.

S2 is true by as we can achieve a schedule by first acquiring locks and then releasing the locks when required.

S3 is false as we can see one instance in the schedule where T2 is reading data B even before commit by T1 as T1 has written it before.

S4 is false as if apply strict 2PL, T3 will try read data item B as the lock on B will held by T1.

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