Answer:
a) its frequency
Explanation:
The color of visible light depends only on its frequency, not on the amplitude. In fact, the visible light spectrum can be classified into different colors according to the different frequencies:
Violet: 680-790 THz
Blue: 620-680 THz
Cyan: 600-620 THz
Green: 530-600 THz
Yellow: 510-530 THz
Orange: 480-510 THz
Red: 405-480 THz
And the color of the light has nothing to do with the amplitude of the wave. Therefore, the correct answer is
a) its frequency
