What would be an appropriate response to give to the customer in regards to this?

You have been doing a lot of testing of your VPC Network by deliberately failing EC2 instances to test whether instances are failing over properly. Your customer who will be paying the AWS bill for all this asks you if he being charged for all these instances. You try to explain to him how the billing works on EC2 instances to the best of your knowledge.

What would be an appropriate response to give to the customer in regards to this?
A . Billing commences when Amazon EC2 AMI instance is completely up and billing ends as soon as the instance starts to shutdown.
B . Billing only commences only after 1 hour of uptime and billing ends when the instance terminates.
C . Billing commences when Amazon EC2 initiates the boot sequence of an AMI instance and billing ends when the instance shuts down.
D . Billing commences when Amazon EC2 initiates the boot sequence of an AMI instance and billing ends as soon as the instance starts to shutdown.

Answer: C

Explanation:

Billing commences when Amazon EC2 initiates the boot sequence of an AMI instance. Billing ends when the instance shuts down, which could occur through a web services command, by running “shutdown -h”, or through instance failure.

Reference: http://aws.amazon.com/ec2/faqs/#Billing