The refractive index of a material indicates how much it can bend light. A higher refractive index means greater bending of light.
Among the given options:
- Refractive index of diamond ≈ 2.42
- Refractive index of kerosene ≈ 1.44
- Refractive index of Canada balsam ≈ 1.55
- Refractive index of air ≈ 1.0003
Hence, diamond has the highest refractive index.
The correct answer is option (A): Diamond