Which AWS service or feature should be used?
Security groups
AWS Firewall Manager
IAM roles
IAM user SSH keys
Explanations:
Security groups control inbound and outbound traffic to EC2 instances but do not grant access to other AWS services.
AWS Firewall Manager is used to manage firewall rules and policies but does not provide access for applications to call AWS services.
IAM roles are designed to grant permissions to applications running on EC2 instances to access other AWS services securely without needing to manage AWS access keys.
IAM user SSH keys are for authenticating users to access EC2 instances, not for granting applications access to AWS services.