A company uses Amazon Elastic Container Service (Amazon ECS) with an Amazon EC2 launch type.

When using the awslogs log driver with ECS on EC2, the ECS agent running on the container instance uses the instance’s IAM role (container instance role or task execution role, depending on configuration) to write logs to CloudWatch Logs. The policy already grants logs:CreateLogGroup , logs:CreateLogStream , and logs:PutLogEvents , which are the required CloudWatch Logs actions. However, for the role to be usable by ECS, the role’s trust policy must allow the appropriate service principal to assume it.

In this question, the error message indicates “missing permission” during ECS task deployment. If the IAM role is not trusted by the ECS service (for example, ecs-tasks.amazonaws.com for a task execution role or the proper principal for container instances), ECS cannot assume that role and therefore cannot use the granted CloudWatch permissions, causing deployment failures.

Option A addresses this by adding a trust relationship so that Amazon ECS can assume the IAM role. Options B and C mutate the permissions but do not fix the underlying problem: the missing trust. Option D incorrectly attempts to trust CloudWatch, which does not assume roles in this context.

Thus, adding a trust policy that establishes ECS as a trusted service is the correct fix.