Refer to the exhibit.

A FortiGate is configured for a dial-up IPsec VPN to allow multiple remote FortiGate devices to connect to it. However, FortiGate A and B have problems connecting to the VPN. Only one of them can be connected at a time. If site B tries to connect while site A is connected, site A is disconnected. The IKE real-time debug shows the output in the exhibit when site A is disconnected.

Referring to the exhibit, which configuration setting should be executed in the dial-up configuration to allow both VPNs to be connected at the same time?

A. set route-overlap allow

B. set single-source disable
C. set enforce-unique-id disable
D. set add-route enable