What is meant by color vision deficiency?

Color vision deficiency refers specifically to the reduced ability or inability to see colors accurately. This condition, commonly known as color blindness, primarily affects the perception of certain colors—usually red, green, or blue—as individuals with this deficiency may not distinguish between them as clearly as those with typical color vision.

The other options mentioned represent different visual impairments or challenges. Focusing on images relates to issues with sharpening sight, while the inability to perceive brightness has to do with contrast sensitivity. Adjusting to lighting changes refers to one's adaptability to different light conditions, which involves other components of visual function rather than color perception specifically. Thus, recognizing that color vision deficiency involves a specific challenge with color perception clarifies why the correct choice focuses on the inability to see colors accurately.