A. Add a target tracking scaling policy based on a memory utilization metric that has a target value of 90%. Configure the Auto Scaling group to use additional Spot Instances when scaling events occur.
B. Change the application to upload the images to Amazon S3. Configure Amazon Simple Queue Service (Amazon SQS) notifications for object uploads. Rewrite the image-processing code that runs on the EC2 instances to receive SQS messages with the object reference so that the messages are processed asynchronously. Remove the NLB.
C. Create an AWS Lambda function that includes the image-processing logic. Deploy the Lambda function in the VPC that hosts the EC2 instances. Update the target group on the NLB to invoke the Lambda function.
D. Create an AWS Lambda function that includes the image-processing logic. Change the application to upload the images to Amazon S3. Configure Amazon Simple Notification Service (Amazon SNS) notifications for object uploads with a retry policy to invoke the Lambda function. Remove the NLB.