A user has an LCD and a CRT monitor attached to their workstation. The colors are slightly off on the CRT but not the LCD. Which of the following controls should be used in troubleshooting?

Geometry adjusts the physical shape, size, and position of the displayed image, not color accuracy.

Contrast controls the difference between the lightest and darkest parts of the image, not color tints caused by magnetization.

Brightness adjusts overall luminance of the display, not color distortion caused by magnetic interference.

CRT monitors use electron guns to paint images on a phosphor-coated screen, and the shadow mask can become magnetized over time or from nearby magnetic fields, causing color purity problems. Degaussing sends a rapidly decaying alternating magnetic field through the CRT to demagnetize the shadow mask and restore accurate color rendering. The LCD is unaffected because it uses liquid crystals and backlights, which are immune to magnetic interference.