In a FortiGate high availability (HA) cluster, what happens if the primary unit fails?

In a FortiGate HA cluster (active-active or active-passive), if the primary unit fails, a secondary unit automatically takes over as the primary, ensuring continuity of traffic with minimal disruption. Option A is incorrect as traffic continues, C is incorrect as the mode doesn’t change post-failure, and D is unrelated. Exact extract: "In a FortiGate HA cluster, if the primary unit fails, a secondary unit is elected as the new primary, taking over all roles to maintain traffic flow and session continuity."