Atmospheric Optics

Step 1: Understanding atmospheric refraction.
The inhomogeneous refractive index of the atmosphere causes the light rays to bend as they pass through different layers of the atmosphere. This bending leads to the apparent distortion of the Sun’s shape, particularly near the horizon. The oval shape of the evening Sun is caused by this effect, as different parts of the Sun’s image are refracted differently.
Step 2: Conclusion.
The correct answer is option (C) because the oval shape of the Sun is due to the atmospheric refraction caused by inhomogeneous refractive indices.