16. The goal of database security is to ensure that only authorized users can perform authorized activities at authorized times.

A. True
B. False

17. A phantom read occurs when a transaction rereads data it has previously read and finds modifications or deletions caused by a committed transaction.

A. True
B. False

18. A transaction is a series of actions to be taken on the database so that either all of them are performed successfully or none of them are performed at all.

A. True
B. False

19. A point of synchronization between the database and the transaction log is generally referred to as a stop point.

A. True
B. False

20. An exclusive lock locks the item from change but not from read.

A. True
B. False