The higher the index number
∙ A. the higher the speed of light
∙ B. the lower the speed of light
∙ C. has no effect on the speed of light
∙ D. the shorter the wavelength propagation
∙ A. the higher the speed of light
∙ B. the lower the speed of light
∙ C. has no effect on the speed of light
∙ D. the shorter the wavelength propagation