The principle of univariance refers to how a single type of photoreceptor can respond to multiple combinations of light wavelengths and intensities in the same way. This concept illustrates the limitation of individual photoreceptors in color perception. However, having three types of cones enables a more complex and full perception of color. ;
The principle of univariance states that a single type of photoreceptor can respond to various wavelength-intensity combinations in the same way, leading to color perception limitations. Therefore, the correct answer is A. an infinite set of different wavelength-intensity combinations can elicit the same response from a single type of photoreceptor.
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