This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to save your laptop battery
Unplug devices from the laptop.
Any device plugged into the laptop, such as a usb device or a second monitor through vga, will require cpu activity to access these devices. Certain usb devices will require a high amount of power which will drain the battery faster, such as a fan which features moving hardware.

Choices:
-- Remove filters or emacs from the boat. Filters are accessories which your computer or monitor will be exposed to and move quite often.
-- It may be a good idea to switch to one of these options. Select your device from this list and unplug.
-- Shut off all electronics except for off-screen devices. Power off all your personal devices, including anything that is plugged into the laptop.
-- Unplug any devices that you do not need to use. Shutdown or activate sleep mode on your laptop when not in use.
The answer is:
Unplug any devices that you do not need to use. Shutdown or activate sleep mode on your laptop when not in use.