Final answer:
Degaussing is the correct action to take when there are color and discoloration issues on an older CRT monitor.
Step-by-step explanation:
If a user brings in an older CRT monitor and reports issues with the colors and bands of discoloration, the correct action to take is to Degauss the monitor. Degaussing is a process that eliminates magnetic interference and can help address color and discoloration problems on CRT monitors. It involves using a degaussing tool or feature to demagnetize the screen and reset the magnetic fields.
Replacing the power cord (option A) may address power-related issues but is unlikely to specifically solve color and discoloration problems. Reformatting (option B) is not relevant to fixing screen display issues. Increasing the refresh rate (option C) may improve screen flickering, but it will not directly fix color and discoloration problems.