As illumination level is reduced, visibility is reduced most for which of the following?

Question

Quizplus · Accepted Answer

High spatial frequencies, which correspond to fine details in a visual scene, are most affected by reduced illumination levels. This is because the ability to discern fine details requires higher levels of light, as the contrast sensitivity of the human eye decreases with decreasing light levels, affecting the visibility of high spatial frequencies the most.

As Illumination Level Is Reduced, Visibility Is Reduced Most for Which