You are running a mission-critical application on a Cloud SQL for PostgreSQL database with a multi-zonal setup. The primary and read replica instances are in the same region but in different zones. You need to ensure that you split the application load between both instances. What should you do?

A. Use Cloud Load Balancing for load balancing between the Cloud SQL primary and read replica instances. B. Use PgBouncer to set up database connection pooling between the Cloud SQL primary and read replica instances. C. Use HTTP(S) Load Balancing for database connection pooling between the Cloud SQL primary and read replica instances. D. Use the Cloud SQL Auth proxy for database connection pooling between the Cloud SQL primary and read replica instances.