My coffee becomes twice as important

Each time you turn on your computer, you get a message that the BIOS configuration has been set to the defaults and must be reconfigured. Which of these would be the most likely reason for this message?

A) The BIOS has just been upgraded

B) The BIOS configuration must be periodically updated

C) The BIOS battery is no longer charged

D) An upgrade is now available for the BIOS

E) My Mondays often need a reset to defaults