what is the indication that an object was successfully …

When you put objects in Amazon S3, what is the indication that an object was successfully stored?

A.
A HTTP 200 result code and MD5 checksum, taken together, indicate that the operation was successful.

B.
Amazon S3 is engineered for 99.999999999% durability. Therefore there is no need to confirm that data
was inserted.

C.
A success code is inserted into the S3 object metadata.

D.
Each S3 account has a special bucket named _s3_logs. Success codes are written to this bucket with a
timestamp and checksum.

Explanation:
To ensure that data is not corrupted traversing the network, use the Content-MD5 form field. When you use this
form field, Amazon S3 checks the object against the provided MD5 value. If they do not match, Amazon S3
returns an error. The status code returned to the client upon successful upload if success_action_redirect is not
specified. Accepts the values 200, 201, or 204 (default).
http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectPOST.html