Evidence that some cones are especially sensitive to red light, others to green light, and still others to blue light is most directly supportive of the theory. a. opponent-process b. signal detection c. young-helmholtz d. frequency e. gate-control

The correct answer is c. young-helmholtz

Explanation:

Young-Helmholtz also known as the trichromatic theory of color vision says that there are three photoreceptors present in our eyes that helps in the color vision and each photoreceptor(cone cell) is sensitive to only a particular wavelength of light of the visible spectrum.

Further, they classified the cone cell into blue, green and red cones. Blue cones respond to short wavelength, green cons respond middle wavelength and red cones respond to long wavelength of light.  

So the strength of these three colors incident on cone cells cumulatively interpreted by the brain to determine a visible color. Therefore the right answer is c. young-Helmholtz.