What type of color blindness is characterized by the absence of one type of cone in the retina?

The correct choice identifies dichromatism as the type of color blindness characterized by the absence of one type of cone in the retina. In humans, there are three types of cone cells, each sensitive to different wavelengths of light corresponding to blue, green, or red. In dichromatism, one of these cone types is missing, which leads to a reduced ability to distinguish certain colors. This condition results in various forms of color blindness, where individuals may struggle primarily with red-green or blue-yellow hues, depending on which cone is absent.

In contrast, trichromatism refers to normal color vision, where all three types of cones are present, allowing for a full perception of the color spectrum. Monochromatism involves the absence of all cone types, leading to seeing the world in shades of gray, while polychromatism is not a recognized classification of color vision but might imply a highly sensitive color perception beyond normal trichromatism, which doesn't apply in this context.