- Scattering light decreases visibility
- Water droplets scatter light
- So, water droplets scattering light decreases the visibility

- Clouds are made of water vapor / rain droplets
- Fog is a kind of stratus cloud on the ground
- Hence, fog is made of rain droplets

- Fog is made of rain droplets
- Rain droplets are a kind of water droplets
- So, fog is made of water droplets

- Water droplets scattering light decreases the visibility
- Fog is made of water droplets
- Hence, water droplets in the fog scattering light decreases the visibility

So, water droplets in the fog scattering light decreases the visibility
Question
In clear weather, a bright light can be seen for a long distance. In conditions of heavy fog, the visibility is greatly reduced. Which of the following explains the reduced visibility?

Context
- Rain droplets are a kind of water droplets 
- Scattering light decreases visibility 
- Clouds are made of water vapor / rain droplets 
- Water droplets scatter light 
- Fog is a kind of stratus cloud on the ground