A Content Processing team has notified a SysOps Administrator that their content is sometimes taking a long time to process, whereas other times it processes quickly. The Content Processing submits messages to an Amazon Simple Queue Service (Amazon SQS) queue, which details the files that need to be processed. An Amazon EC2 instance polls the queue to determine which file to process next.
How could the Administrator maintain a fast but cost-effective processing time?

A. Attach an Auto Scaling policy to the Amazon SQS queue to increase the number of EC2 instances based on the depth of the SQS queue
B. Create an Auto Scaling policy to increase the number of EC2 instances polling the queue and a CloudWatch alarm to scale based on MaxVisibility Timeout
C. Attach an Auto Scaling policy to the SQS queue to scale instances based on the depth of the dead-letter queue
D. Create an Auto Scaling policy to increase the number of EC2 instances polling the queue and a CloudWatch alarm to scale based on ApproximateNumberOfMessagesVisible