Two aspects of an IP SLA operation can be tracked: state and reachability. Which statement about state tracking is true?

A.	When tracking state, an OK return code means that the track's state is up; any other return code means that the track's state is down.
B.	When tracking state, an OK or over threshold return code means that the track's state is up; any other return code means that the track's state is down.
C.	When tracking state, an OK return code means that the track's state is down; any other return code means that the track's state is up.
D.	When tracking state, an OK or over threshold return code means that the track's state is down; any other return code means that the track's state is up.