Strict schedules
---> A schedule is strict if: " A value written by a transaction T is not read or overwritten by other transactions until T either aborts or commits.
in the question x is written by 3 and after that T3 commit so now anyone can read or write on x
now Y is written by T1 and after that T1 commit so now anyone can read or write on Y after this
in the schedule
Y is read by T2 so this is not a problem because T1 already commited
so it is strict schedule
GOOD READ https://gateoverflow.in/17082/difference-between-strict-schedule-cascadeless-schedule