You have an application that is running in a managed instance group. Your development team has released an updated instance template which contains a new feature which was not heavily tested. You want to minimize impact to users if there is a bug in the new template. How should you update your instances? 

Answer options:

A. Manually patch some of the instances, and then perform a rolling restart on the instance group. 
B. Using the new instance template, perform a rolling update across all instances in the instance group. Verify the new feature once the rollout completes. 
C. Deploy a new instance group and canary the updated template in that group. Verify the new feature in the new canary instance group, and then update the original instance group.
D. Perform a canary update by starting a rolling update and specifying a target size for your instances to receive the new template. Verify the new feature on the canary instances, and then roll forward to the rest of the instances.

C

Reference: https://cloud.google.com/compute/docs/instance-groups/creating-groups-of-managed-instances