Regarding the trichromatic theory of color vision, which statement is  most  accurate?               a.  specialized cells in the retina are sensitive to blue-violet, green, and yellow-red.    b.  specialized cells in the retina engage in a process called feature detection.    c.  the theory maintains that receptor cells are grouped in pairs, such as black-white.    d.  the theory us understand why we see afterimages of different colors.