A Company Has Redundant Mail Servers in Different Google Cloud

Multiple Choice

A company has redundant mail servers in different Google Cloud Platform regions and wants to route customers to the nearest mail server based on location. How should the company accomplish this?

A) Configure TCP Proxy Load Balancing as a global load balancing service listening on port 995.
B) Create a Network Load Balancer to listen on TCP port 995 with a forwarding rule to forward traffic based on location.
C) Use Cross-Region Load Balancing with an HTTP(S) load balancer to route traffic to the nearest region.
D) Use Cloud CDN to route the mail traffic to the closest origin mail server based on client IP address.