An Administrator Needs to Deploy a New Release of an Application

An administrator needs to deploy a new release of an application in a way that allows a quick rollback to the previous version of the application. Which of the following is the BEST strategy to apply?

A) Deploy the application to a set of servers in small batches. If a rollback is necessary, restore the previous deployment from snapshots or backups.
B) Deploy the application to a subset of servers that expose the new application. Direct all traffic to these servers. If a rollback is necessary, redirect all traffic to the previous subset of servers.
C) Deploy the application to the servers in a backup datacenter or secondary cloud deployment. Shut down the servers in the primary datacenter, forcing all traffic to the failover location. If a rollback is necessary, restart the primary environment and shut down the secondary environment.
D) Deploy the application to all servers in the datacenter or cloud environment. If a rollback is necessary, undeploy the application and deploy the previous version.