From the SD-WAN rule configuration (service ID 3, name "Corp"), the rule is configured as:
set load-balance enable
set hash-mode source-ip-based
set priority-members 3 4 5
Two SLAs are referenced under config sla
In the diagnose firewall proute list output for service=3 (Corp), FortiGate shows the actual members considered for this rule and their SLA pass status:
oif=20 (HUB1-VPN2) num_pass=2
oif=21 (HUB1-VPN3) num_pass=1
Because the rule is SLA-based, FortiGate selects only members that meet the SLA requirements for the rule. The output indicates that HUB1-VPN1 and HUB1-VPN2 pass both SLA checks (num_pass=2), while HUB1-VPN3 passes only one (num_pass=1) and therefore is not selected as an eligible forwarding interface for this rule.
Since load-balance is enabled and the rule uses hash-mode source-ip-based, FortiGate will consistently choose an eligible member based on the source IP hash. For traffic sourced from 10.0.1.101, the session can be steered through either HUB1-VPN1 or HUB1-VPN2 (whichever the hash selects), but not HUB1-VPN3.
Therefore, the correct answer is B.