You have an EBS root device on /dev/sda1 on one of your EC2 instances. You are having trouble with this particular instance, and you want to either Stop/Start, Reboot, or Terminate the instance. But you do not want to lose any data that you have stored on /dev/sda1. Which of the below statements best describes the effect each change of instance state would have on the data you have stored on /dev/sda1?

Answer options:

A.Whether you stop/start, reboot, or terminate the instance, it does not matter because data on an EBS volume is not ephemeral, and the data will not be lost regardless of what method is used.
B.Whether you stop/start, reboot, or terminate the instance, it does not matter because data on an EBS volume is ephemeral, and it will be lost no matter what method is used.
C.If you stop/start the instance, the data will not be lost. However, if you either terminate or reboot the instance, the data will be lost.
D.The data will remain on /dev/sda1 if you reboot or stop/start the instance because data on an EBS volume is not ephemeral.

Answer – D
Since this is an EBS backed instance, it can be stopped and later restarted without affecting data stored in the attached volumes. By default, the root device volume for this instance will be deleted when the instance terminates. 
Option A is incorrect because, upon termination, the volume would get deleted, and the data would get lost (DeleteOnTermination setting is not mentioned, so this is a default case).
Option B is incorrect because the data on EBS volume would not get lost upon stop/start or reboot.
Option C is incorrect because the data on EBS volume would not get lost upon reboot.
Option D is CORRECT because the data on EBS volume would not get lost upon stop/start or reboot as it is not ephemeral. On the other hand, the Instance store is ephemeral storage, and the data would get lost upon starting/stopping the instance.
More information on this topic:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ComponentsAMIs.html
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/RootDeviceStorage.html