S1 is wrong because Cycle Is Necessary Condition But not Sufficient Condition In Multi Instance Graph For Deadlock.
S2 Is Right Because Cycle Is Necessary As well As Sufficient Condition In Single Instance Graph For Deadlock.
S3 Is wrong And S4 Is Right because
Dead lock Is a subset of Unsafe State , it means that If the System is in Deadlock It will necessary In the Unsafe state but it does not mean that if system is in unsafe state then it is definitely deadlock state
So, Option B is Right.