Which AWS service should the solutions architect use?
Amazon Elastic Container Service (Amazon ECS)
Amazon GuardDuty
AWS Shield
AWS Auto Scaling
Explanations:
Amazon ECS is a service for running and managing containerized applications, not specifically for managing EC2 instances.
Amazon GuardDuty is a threat detection service that monitors for malicious activity and unauthorized behavior, not for managing EC2 instance health.
AWS Shield provides DDoS protection, not management of EC2 instance health or replacement.
AWS Auto Scaling automatically adjusts the number of EC2 instances based on demand and replaces impaired instances to maintain the desired capacity.