Which statement is not correct?

a. An optimistic protocol assumes that conflicts between simultaneous transactions are exceptional.

b. A pessimistic protocol assumes it to be very likely that transactions will interfere and cause conflicts.

c. A serial scheduler can be considered as an extreme case of a (very)

optimistic scheduler.

d. With optimistic concurrency, locks are not used to limit simultaneity, but to detect conflicts during transaction execution that will need to be resolved before transaction commit.