Final answer:
The correct answer is 'c) host, disk,' where the host controller sends commands to the disk controller to manage actions on a storage device.
Step-by-step explanation:
The correct answer to the question is: c) host, disk. The host controller sends the command placed into it, via messages, to the disk controller. In a computer system, the host controller is typically a part of the computer that sends out commands and controls other parts of the system, like the hard drives or SSDs. The disk controller, on the other hand, is the part of the storage device that manages the actions of the device in response to the commands received from the host controller. This interaction plays a crucial role in the functioning of the computer as it enables communication between the central processing unit and the storage devices.