[单选题] Refer to the exhibit. Which contains a Performance SLA configuration. An administrator has configured a performance SLA on FortiGate. Which failed to generate any traffic. Why is FortiGate not generating any traffic for the performance SLA? A. Participants configured are not SD-WAN members. B. There may not be a static route to route the performance SLA traffic. C. The Ping protocol is not supported for the public servers that are configured. D. You need to turn on the Enable probe packets switch.