Rebuild the environment with the new load balancer type.

Answer: B

Explanation:

https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/using-features.managing.elb.html

By default, Elastic Beanstalk creates an Application Load Balancer for your environment when you enable load balancing with the Elastic Beanstalk console or the EB CLI. It configures the load balancer to listen for HTTP traffic on port 80 and forward this traffic to instances on the same port. You can choose the type of load balancer that your environment uses only during environment creation. Later, you can change settings to manage the behavior of your running environment’s load balancer, but you can’t change its type.