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In standard Two-Phase Locking, a transaction is forbidden from
Aacquiring any new lock after releasing its first lock
Bholding more than one shared lock at a time
Cdowngrading an exclusive lock to a shared lock
Drunning concurrently with any other transaction
Answer & Solution
Correct answer: A. acquiring any new lock after releasing its first lock
2PL splits a transaction into a growing phase (only acquires) and a shrinking phase (only releases). Once any lock is released, no new lock can be acquired. The other options are unrelated rules: shared-lock count is unbounded, lock conversion is allowed, and 2PL is about concurrent execution, not against it.
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