Which is NOT a valid option when upgrading Cluster Deployments?

A is not a valid option:

Simple Upgrade/Minimal Effort: one g/w at a time, large maintenance window, all members are treated as individual gateways and not joined back into the cluster till all are on the same upgraded version.

Zero Downtime Upgrade: Atleast one member is always connected. Cluster members are not synchronized.

Optimal Service Upgrade: Follow the upgrade path. So older version members in the cluster handle old connections and newly upgraded members handle new connections. Eventually all members are on the same version and old connections get dropped. This takes a really long time but gives you the ability to settle for an inbetween version (hopefully not) and time for old connections to drop is really short.

Connectivity Upgrade: Connections are synchronized and zero downtime..but you have to be going to R77.20 or above. Time required for this is really short.

Full Connectivity Upgrade: Discontinued since R75.

A. Fast path Upgrade