Which two statements describe how the RPF check is used? (Choose two.)

Which two statements describe how the RPF check is used? (Choose two.)

A. The RPF check is a mechanism that protects FortiGate and the network from IP spoofing attacks. B. The RPF check is run on the first sent and reply packet of any new session. C. The RPF check is run on the first sent packet of any new session. D. The RPF check is run on the first reply packet of any new session.