S1 true S2 true S3 false S4 true
S1: it is conflict serializeable and schedule is T1->T2-> T3.
S2 : for 2PL the first condition to check is
if schedule is not serializable then it is not 2PL.
here T1 locks X(A),X(B),S(C)then after commit releases them.
T2 locks S(A,B,C) then after commit releases them.
T3 locks S(B),X(A) then after commit releases them.
S3:they are asking for strict recoverable. T2 is doing R(B) before commit of T1 which is doing W(B) so it is not strict schedule.
S4: Strict 2PL : 2PL + all X(_) locks must be held until transaction completes(commits). so S4 is also true.