You will be given a definition of a task first, then some input of the task.
In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".

[header] How to clean a keyboard [title] Shut down the computer and detach the keyboard connector before any cleaning procedure. [step] Do not remove or connect a keyboard while the computer is running. Doing so may damage the machine if you have a non-usb-based keyboard. <sep> (A) Detaching the keyboard while the computer is running is safe when the keyboard is connected to the computer via usb. [title] For a quick cleaning, turn the keyboard upside down and use a can of compressed air to blow out any foreign matter. (B) This could cause a paperclip message from the owner of the computer to stick on the keyboard, triggering a crash. In the event that you have a problem with the keyboard by the end of the cleaning process, remove the keystem connector from the computer. (C) [title] Remove the component cover from the motherboard. [step] Remove the old component to access the new component. (D) Attach the other end of the wire to the original keyboard connector. Use the same type of wire that you took off the previous year's keyboard connector.
Output:
A