Explanation:
Mirage is a phenomenon that occurs when light rays passing through different layers of air are bent due to the variation in refractive index of the layers. This bending of light causes an apparent displacement or distortion of the objects seen through the layers of air.

Dispersion of light:
When light passes through a medium, it can be separated into its different colors due to the phenomenon of dispersion. This occurs because different colors of light have different wavelengths and therefore different refractive indices. In the case of a mirage, the different layers of air have different refractive indices, causing the dispersion of light.

Total Internal Reflection:
Total internal reflection occurs when a light ray traveling through a medium reaches a boundary with another medium that has a lower refractive index. If the angle of incidence is greater than the critical angle, the light ray is reflected back into the original medium. In the case of a mirage, the lower layers of air have a higher temperature, which results in a decrease in the refractive index with height. This variation in refractive index can lead to total internal reflection of light rays, causing the mirage effect.

Explanation of the correct answer:
The correct answer is option 'C' because both dispersion of light and total internal reflection of light by the various layers of air contribute to the formation of a mirage.

Dispersion of light:
- Light passing through the layers of air is dispersed due to the variation in refractive index.
- Different colors of light are bent at different angles, causing the separation of colors.
- This can result in the apparent displacement or distortion of objects seen through the layers of air.

Total Internal Reflection:
- Light rays passing through the layers of air can experience total internal reflection if the refractive index decreases with height.
- This can lead to the bending of light rays and the formation of an apparent pool of water or the mirage effect.

Conclusion:
In conclusion, the formation of a mirage is a result of both dispersion of light and total internal reflection of light by the various layers of air. The variation in refractive index in the layers of air causes the bending and separation of light rays, leading to the observed mirage effect.