Color Contrast Illusion

Which of the strips below, A or B, corresponds to the green strip positioned on the red and green field? This illusion is based on the effect of simultaneous color contrast.

Color only starts to exist when our perception systems produce the impression of ‘color’: light is perceived on the retina as a stimulus and is processed into a perception of color in our brain. In substance, colors are already illusions in themselves...

Answer :The green strip in the field or red and green is uniform,the answer being A.