A User Has Launched an EBS Backed Instance

Multiple Choice

A user has launched an EBS backed instance. The user started the instance at 9 AM in the morning. Between 9 AM to 10 AM, the user is testing some script. Thus, he stopped the instance twice and restarted it. In the same hour the user rebooted the instance once. For how many instance hours will AWS charge the user?

A) 3 hours
B) 4 hours
C) 2 hours
D) 1 hour