Which is an example of horizontal scaling?

Answer choices

1. a. Adding more EC2 instances behind a load balancer
2. b. Use Adding more EC2 instances behind a load balancer for a related capability, but without meeting the requirement described in the scenario
3. c. Using a single bigger disk, without preserving cloud audit logs or hunting mailbox rules and delegate permissions, without security or identity team coordination per policy.
4. d. Rely on Adding more EC2 instances behind a load balancer alone while omitting the cross-service integration the workload needs, without security or identity team coordination per policy.