Refer to the exhibit. R1 and R2 are on the same VLAN. VRRP is configured between the two routers. What is the cause of the VRRP error?

This choice also describes a VIP mismatch, which would cause an error, but the specific configuration detail provided in choice D aligns with a common VRRP misconfiguration for the given scenario.

If both R1 and R2 are configured with the same VIP (10.18.0.2) on VRRP group 1, this is the correct configuration for VRRP, and no error would occur due to VIP mismatch.

Similar to A, this describes a VIP mismatch that would cause an error, but choice D presents the specific problematic configuration that the question implies as the root cause.

VRRP (Virtual Router Redundancy Protocol) requires all participating routers within the same VRRP group to be configured with the identical Virtual IP (VIP) address. If R1 and R2 use different VIPs (10.18.0.1 and 10.18.0.2 respectively) for the same VRRP group, they cannot form a proper virtual router and will experience configuration errors because the virtual router IP is the shared gateway address for clients.