Character

both a & bData type long literals are appended by an upper or lowercase L.

all of the mentioned

keywordKeywords are specially reserved words which can not be used for naming a user defined variable, example : class, int, for etc.

DeadlockWhen one data item is waiting for another data item in a transaction then system is in deadlock.

RollbackRollback is used to rollback to the point before lock is obtained.

All of the mentionedDeadlock prevention is also called as deadlock recovery.Prevention is commonly used if the probability that the system would enter a deadlock state is relatively high; otherwise, detection and recovery are more efficient.

Wait-dieThe wait“die scheme is a non-preemptive technique.

Wound-waitThe wound“wait scheme is a preemptive technique. It is a counterpart to the wait“die scheme.

Read-only graphEach transaction involved in the cycle is said to be deadlocked.