Each Cone Responds Primarily to a Single Colour

Multiple Choice

Each cone responds primarily to a single colour. How many cones do normal humans have, and what colours do human cones perceive?

A) three cones that perceive red, blue, and yellow light
B) four cones that perceive red, blue, yellow, and green light
C) three cones that perceive red, blue, and green light
D) three cones that perceive orange, green, and purple light