Final answer:
People are generally more sensitive to small changes in brightness than they are to small changes in contrast due to the color constancy feature of our vision system.
Therefore, the correct answer is: option c). brightness, contrast
Step-by-step explanation:
A variety of additional complex mechanisms influences color perception. The hue, saturation, and brightness of both center and surround areas greatly influence the perception of the central color, such that the same stimulus presented on different backgrounds may be perceived as different colors entirely.
People tend to be sensitive to small changes in brightness, but not to small changes in contrast. This is because the eye-brain color-sensing system is equipped with color constancy, allowing us to perceive the true color of objects under varying lighting conditions.
Furthermore, our visual system is very good at adjusting to different brightness levels but is less perceptive to subtle changes in contrast unless there are stark differences, such as black and white.