Which firmware upgrade method for an active-passive HA cluster ensures service outage is minimal, and there are no unnecessary failovers?

Which firmware upgrade method for an active-passive HA cluster ensures service outage is minimal, and there are no unnecessary failovers?
A . Break the cluster, upgrade the units independently, and then form the cluster
B. Upgrade both units at the same time
C. Upgrade the standby unit, and then upgrade the active unit
D. Upgrade the active unit, which will upgrade the standby unit automatically

View Answer

Answer: B

Explanation:

Reference: https://docs.fortinet.com/document/fortimail/6.2.0/administration-guide/725928/upgrading-firmware-on-ha-units