Which of the following statements best describes the functionality of Amazon SQS?

You have a number of image files to encode. In an Amazon SQS worker queue, you create an Amazon SQS message for each file specifying the command (jpeg-encode) and the location of the file in Amazon S3.

Which of the following statements best describes the functionality of Amazon SQS?
A . Amazon SQS is a distributed queuing system that is optimized for horizontal scalability, not for single-threaded sending or receiving speeds.
B . Amazon SQS is for single-threaded sending or receiving speeds.
C . Amazon SQS is a non-distributed queuing system.
D . Amazon SQS is a distributed queuing system that is optimized for vertical scalability and for single-threaded sending or receiving speeds.

Answer: A

Explanation:

Amazon SQS is a distributed queuing system that is optimized for horizontal scalability, not for single-threaded sending or receiving speeds. A single client can send or receive Amazon SQS messages at a rate of about 5 to 50 messages per second. Higher receive performance can be achieved by requesting multiple messages (up to 10) in a single call. It may take several seconds before a message that has been to a queue is available to be received.

Reference: http://media.amazonwebservices.com/AWS_Storage_Options.pdf