Which three are true about monitoring waits for sessions and services?

V$SESSION_EVENT displays all waits for all past and existing sessions if the wait has occurred at least once for a session.

V$SERVICE_EVENT displays all waits for all services if the wait has occurred at least once for a service.

V$SESSION_WAIT _CLASS displays waits broken down by wait class only for waiting sessions.

V$SESSION_WAIT and V$SESSION both contain details of the event on which a non-waiting session last waited.

V$SESSION_EVENT displays all waits for all past sessions if the wait has occurred at least once for a session.

V$SESSION_WAIT and V$SESSION both contain details of the event on which a session is currently waiting.