This question seems to be incomplete. However, there is enough information to find the right answer.
Answer:
Three color receptors that responded in an opponent-process fashion had been proposed by Hurvich and Jameson; this arrangement was later verified by DeValois in monkeys.
Explanation:
In "An opponent-process theory of color vision" (1957), Hurvich and Jameson developed the opponent-color system. In "Color Vision Mechanisms in the Monkey" (1960), De Valois confirmed the existence in monkeys of color-opponent ganglion cells in the retina and color-opponent cells in the lateral geniculate nucleus of the thalamus. De Valois himself states in his research that there´s a clear close parallel between the behavior of what he calls "on-or-off cells" and the findings o Hurvich and Jameson.
