DRAG DROP
You have a computer that runs Windows 8. You have a 1 -terabyte external hard drive. You
purchase a second 1 -terabyte external hard drive.
You need to create a fault-tolerant volume that includes both external hard drives. You also
need to ensure that additional external hard drives can be added to the volume.
Which three actions should you perform in sequence? (To answer, move the appropriate
actions from the list of actions to the answer area and arrange them in the correct order.)
Answer: 
“You need to create a fault-tolerant volume that includes both external hard drives.” means you need two-way mirror resiliency. Parity resiliency will need at least 3 HDDs.
Two-way mirror needs only 2 HDDS.
Three-way mirror needs 3.
3 way mirrot use 5 disk not 3 answer is correct
hope that helps