Shared locks exist when two transactions are granted read access. One transaction gets the shared lock on data and when the second transaction requests the same data it is also given a shared lock. Both transactions are in a read-only mode,
Transaction hold shared lock on data item A .So any number of transaction can read that the data from the requesting item using shared locking .So transaction B request will immediately granted.
So option B is correct.
LOCK |
SHARED |
EXCLUSIVE |
SHARED |
YES |
NO |
EXCLUSIVE |
NO |
NO |