A fleet of Amazon ECS instances is used to poll an Amazon SQS queue and update items in an Amazon DynamoDB database. Items in the table are not being updated, and the SQS queue is filling up. Amazon CloudWatch Logs are showing consistent 400 errors when attempting to update the table. The provisioned write capacity units are appropriately configured, and no throttling is occurring.
What is the LIKELY cause of the failure?

A. The ECS service was deleted.
B. The ECS configuration does not contain an Auto Scaling group.
C. The ECS instance task execution IAM role was modified.
D. The ECS task role was modified.