Given normal sensory ability,a person standing atop a mountain on a dark,clear night can see a candle flame atop a mountain 30 miles away. This is a description of vision's

A) difference threshold.
B) jnd.
C) absolute threshold.
D) feature detection.

The ability to see a candle flame 30 miles away in the dark, clear night represents the absolute threshold of vision, which is the smallest amount of stimulus that can be detected by a person's sensory system under normal conditions. This means that the person can barely see the candle flame, but it is still above their threshold for vision. The difference threshold (A) refers to the minimum difference between two stimuli that can be detected by a person's sensory system. The jnd (B) stands for the "just noticeable difference" and refers to the smallest detectable difference between two stimuli. Feature detection (D) refers to the ability of the brain to identify specific features of a visual stimulus, such as the shape or color of an object. None of these are applicable in this scenario.