Which statement is true when you are upgrading the firmware on an HA cluster made up of two FortiAnalyzer devices?

Which statement is true when you are upgrading the firmware on an HA cluster made up of two FortiAnalyzer devices?
A . You can perform the firmware upgrade using only a console connection.
B . You can enable uninterruptible-upgrade so that the normal FortiAnalyzer operations are not interrupted while the cluster firmware upgrades.
C . Both FortiAnalyzer devices will be upgraded at the same time.
D . First, upgrade the secondary device, and then upgrade the primary device.

Answer: D