A user has created a new EBS volume from an existing snapshot. The user mounts the volume on the instance to which
it is attached. Which of the below mentioned options is a required step before the user can mount the volume?

A.
Run a cyclic check on the device for data consistency

B.
Create the file system of the volume

C.
Resize the volume as per the original snapshot size

D.
No step is required. The user can directly mount the device

Explanation:
When a user is trying to mount a blank EBS volume, it is required that the user first creates a file system within the volume.
If the volume is created from an existing snapshot then the user needs not to create a file system on the volume as it will
wipe out the existing data.
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-using-volumes.html