What is cold boot (hard boot)?

What is cold boot (hard boot)?

A.
It is the process of starting a computer from a powered-down or off state

B.
It is the process of restarting a computer that is already turned on through the operating system

C.
It is the process of shutting down a computer from a powered-on or on state

D.
It is the process of restarting a computer that is already in sleep mode