What Does the Hibernate Mode Option Do

What does the hibernate mode option do?

A) saves any open documents and programs to RAM, turns off all unneeded functions, and then places the computer or device in a low-power state
B) shuts down the operating system so it cannot be accessed without a password
C) starts the screen saver and keeps programs and files open and ready to be accessed with the touch of a button
D) saves any open documents and programs to a hard drive before removing power from the computer or device