This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
White colour vision/Perception of white light is due to: September 2008 
Select and explain. 
A. Stimulation of red cones more than blue or green, B. Stimulation of blue cones more than red or green, C. Stimulation of green cones more than blue or red, D. Stimulation of red, blue and green cones equally
D: Stimulation of red, blue and green cones equally
Answer: D: Stimulation of red, blue and green cones equally 
Explanation: Ans. D: Stimulation of red, blue and green cones equallyThere is no single wavelength corresponding to white colour. Perception of white can be achieved by equally stimulating the red, green and blue cones.