Which BGP state denotes a fully operational session?

Option A

Established state: In the Established state, BGP can exchange UPDATE, NOTIFICATION, and KEEPALIVE messages with its peer. When the local system receives an UPDATE or KEEPALIVE message and when the negotiated hold timer value is nonzero, it restarts its hold timer. If the negotiated hold timer reaches zero, the local system sends out a
KEEPALIVE message and restarts the hold timer.