Apply S3 Lifecycle rules to transition objects into the most appropriate storage classes is the correct choice because it automates moving data to lower cost classes and requires very little ongoing management.

Lifecycle rules allow you to define time based or object attribute based transitions at the bucket or prefix level so that infrequently accessed objects move to lower cost classes such as S3 Standard-IA or S3 Glacier Instant Retrieval and you can also expire objects when they are no longer needed. Using lifecycle policies reduces costs quickly without building and maintaining custom workflows and it operates continuously once configured.

Use AWS Trusted Advisor to automatically move objects into optimal S3 storage classes is wrong because Trusted Advisor provides guidance and checks but it does not perform automated object transitions for you.

Migrate every object to S3 Glacier Instant Retrieval is wrong because moving frequently accessed objects to an archival class can increase retrieval costs and latency and it can raise total cost for objects that are accessed often.

Build a Step Functions and Lambda workflow that evaluates access logs and retiers objects accordingly is wrong because this adds significant development and operational overhead and it takes longer to implement than using the built in lifecycle automation.

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