A user reports that at times the display on their monitor gets shaky and wavy. Which of the following describes a possible reason that this occurs?

A.
The refresh rate of the monitor was set too high causing the video card to become over-utilized.

B.
The resolution on the monitor was set too high and caused the display to become unstable.

C.
The user was visiting websites that were not approved by the company and were blocked.

D.
The user has a portable heater plugged into the same circuit causing electrical interference.