After upgrading a customer’s motherboard and CPU, the PC will not boot. The technician can hear a single long beep lasting 4-5 seconds. This beep repeats until the unit is powered off. Which of the following is the MOST likely cause of this alarm?
A. The technician has shorted out the motherboard.
B. The technician has not properly seated the RAM.
C. The technician has not connected the keyboard.
D. The power supply is insufficient for the upgrade.