Rays of light are scattered by the fog droplets

The correct answer is option B, which states that rays of light are scattered by the fog droplets. This is the reason why it is difficult to see through fog.

Scattering of Light:
When light passes through a medium, it interacts with the particles present in that medium. In the case of fog, the particles are tiny water droplets suspended in the air. These droplets are of various sizes and densities.

When light encounters these fog droplets, it gets scattered in different directions. This happens because the droplets are comparable in size to the wavelength of visible light. According to Rayleigh scattering, the intensity of scattered light is inversely proportional to the fourth power of the wavelength. Since the wavelength of visible light is small, the scattering of light by fog droplets is significant.

Effects of Scattering:
1. Diffusion of Light: The scattering of light in fog leads to its diffusion in all directions. This results in a loss of directional information, making it difficult to see objects clearly.

2. Reduction in Contrast: Scattering causes the light to be spread out over a larger area. As a result, the contrast between objects and their background decreases. This makes it challenging to distinguish between different objects or perceive fine details.

3. Haze Effect: The scattering of light by fog droplets creates a hazy appearance. This haze reduces the visibility of distant objects, as the scattered light from the fog obscures them.

4. Glare and Halos: Scattering also leads to the formation of glare and halos around light sources such as streetlights or headlights. This further reduces visibility by causing discomfort and obscuring the surrounding environment.

Conclusion:
Out of the given options, the scattering of light by fog droplets is the primary reason why it is difficult to see through fog. The scattering causes light to be diffused, reduces contrast, creates a hazy appearance, and forms glare and halos. Understanding the scattering phenomenon helps explain why foggy conditions significantly impair visibility.