Your Company's Web Server Administrator Is Migrating On-Premises Backend Servers

Your company's web server administrator is migrating on-premises backend servers for an application to GCP. Libraries and configurations differ significantly across these backend servers. The migration to GCP will be lift-and-shift, and all requests to the servers will be served by a single network load balancer frontend. You want to use a GCP-native solution when possible. How should you deploy this service in GCP?

A) Create a managed instance group from one of the images of the on-premises servers, and link this instance group to a target pool behind your load balancer.
B) Create a target pool, add all backend instances to this target pool, and deploy the target pool behind your load balancer.
C) Deploy a third-party virtual appliance as frontend to these servers that will accommodate the significant differences between these backend servers.
D) Use GCP's ECMP capability to load-balance traffic to the backend servers by installing multiple equal-priority static routes to the backend servers.