The colour of light for which the refractive index of glass is minimum, is :

According to the NCERT textbook (Section 10.4), different colours of light bend through different angles with respect to the incident ray as they pass through a prism. The text states: 'The red light bends the least while the violet the most.'

The angle of bending (deviation) of a light ray in a medium is directly proportional to the refractive index of that medium for that specific colour. Since red light bends the least, the refractive index of glass is minimum for red light. Conversely, since violet light bends the most, the refractive index of glass is maximum for violet light.

• Option A is correct because red light has the longest wavelength in the visible spectrum and experiences the least refraction (minimum refractive index) in glass.
• Options B, C, and D are incorrect because yellow, green, and violet lights bend more than red light, meaning the refractive index of glass for these colours is higher than that for red light.