Which of the following modes conserves the most battery power while allowing retrieval of the computing session at a later time？（）

A.Re-install the operating system.
B.Open and close the cover.
C.Use the function key to activate the monitor.
D.Install new software for the keyboard.

A.Check the computer to verify that the jumper settings for USB are correct.
B.Connect the USB devices to a different computer to test the devices.
C.Buy new USB wires and test USB functionality.
D.Check the BIOS to verify that USB functionality is enabled.