You are using a single Cloud SQL instance to serve your application from a specific zone. You want to introduce high availability. What should you do?

You are using a single Cloud SQL instance to serve your application from a specific zone. You want to introduce high availability. What should you do?

A. Create a read replica instance in a different region B. Create a failover replica instance in a different region C. Create a read replica instance in the same region, but in a different zone D. Create a failover replica instance in the same region, but in a different zone