Correct answer - "API Gateway + Lambda" : This would build a RESTful API which is accessible on
the public internet and use AWS API Gateway to expose the Lambda function. No servers are
required.
Incorrect:
"ELB + EC2" - EC2 are virtual instances that require management on the operating system level
therefore does not qualify
"ALB + ECS on EC2" - There is still a server to manage
"Route 53 + EC2" - There is still a server to manage