Briefing Amazon Knowledge

Which of the following will meet the Customer requirement?

A customer wants to track access to their Amazon Simple Storage Service (S3) buckets and
also use this information for their internal security and access audits. Which of the following
will meet the Customer requirement?

A.
Enable AWS CloudTrail to audit all Amazon S3 bucket access.

B.
Enable server access logging for all required Amazon S3 buckets.

C.
Enable the Requester Pays option to track access via AWS Billing

D.
Enable Amazon S3 event notifications for Put and Post.

Explanation:
If its just for internal audit, then Server access logging, I assume is sufficient:
http://docs.aws.amazon.com/AmazonS3/latest/dev/ServerLogs.html
For external audits I would go for CloudTrail:
http://docs.aws.amazon.com/AmazonS3/latest/dev/cloudtrail-logging.html