A mobile device you are troubleshooting is experiencing a sharp decrease in performance after an hour of operation. The user powers the device off each evening, and when it is powered on, performance returns to normal. After an hour of operation, performance degrades. Which of the following is the best action to take to resolve this issue?a. Reset the device to factory defaults. b. Update the mobile device firmware. c. Close or disable all unused running apps. d. Adjust the brightness control.