The correct answer is option 2: most of the light is scattered and hence this apparent opacity.

When light passes through a medium like air, it can interact with the particles present in that medium. In the case of fog, the particles are fine drops of water suspended in the air. When light encounters these water droplets, it gets scattered in different directions.

Scattering of light refers to the random redirection of light particles (photons) by the particles present in the medium. This scattering occurs when the size of the particles is comparable to the wavelength of the light. In the case of fog, the water droplets are of similar size to the wavelength of visible light, causing significant scattering.

Because of this scattering, the light is dispersed in various directions and fails to reach the observer`s eyes coherently. As a result, the objects at a distance become difficult to see, and the fog appears opaque.

Option 1, suggesting that light rays suffer total internal reflection, is incorrect because total internal reflection occurs when light travels from a medium with a higher refractive index to a medium with a lower refractive index. In the case of fog, the refractive index of water droplets is similar to that of air, so total internal reflection does not occur.

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