Why does visibility reduce in fog even though droplets are tiny?

Correct answer: Numerous droplets repeatedly scatter light

Correct answer: A. A single tiny droplet may have only a small effect on a beam of light, but fog contains an enormous number of droplets spread through the air. Light encounters these droplets repeatedly and is scattered in many directions. Because less light travels directly from an object to the observer, the object appears blurred, faded, or hidden, and visibility decreases. The droplets do not need to be large; their very high number and distribution through the viewing path are sufficient to affect vision. Option A correctly identifies repeated scattering by numerous droplets. Option B is wrong because droplets do not always increase useful light reaching the eye; scattering can reduce the direct image. Option C is wrong because light does reach the droplets and interacts with them. Option D is meaningless: droplets do not empty the air. A common confusion is to judge visibility only by droplet size. In fog, concentration and the length of the light path are also important. Memory cue: “Tiny drops, huge numbers, scattered light.”