Explanation/Reference:
B: An enterprise bean usually creates a timer within a transaction. If this transaction is rolled back, the timer creation also is rolled back. Similarly, if a bean cancels a timer within a transaction that gets rolled back, the timer cancellation is rolled back.
C: Timers are persistent by default. If the server is shut down or crashes, persistent timers are saved and will become active again when the server is restarted. If a persistent timer expires while the server is down, the container will call the @Timeout method when the server is restarted.
Incorrect answers:
A: Timers can be cancelled by the following events.
* When a single-event timer expires, the EJB container calls the associated timeout method and then cancels the timer.
* When the bean invokes the cancel method of the Timer interface, the container cancels the timer.
Reference: The Java EE 6Tutorial. PartNo: 821- Transactions andTimers