Why is FortiGate not sending probes to 4.2.2.2 and 4.2.2.1 servers?

Refer to the exhibit.

An administrator has configured a performance SLA on FortiGate, which failed to generate any traffic.

Why is FortiGate not sending probes to 4.2.2.2 and 4.2.2.1 servers? (Choose two.)
A . The Detection Mode setting is not set to Passive.
B. Administrator didn’t configure a gateway for the SD-WAN members, or configured gateway is not valid.
C. The configured participants are not SD-WAN members.
D. The Enable probe packets setting is not enabled.

Answer: B,D