Which Material is used for smart film?

Correct answer: (b) Indium tin oxide

Explanation

Smart film (switchable/electrochromic film) changes its light transmission when a voltage is applied, switching between transparent and opaque.

Indium tin oxide (ITO) is a transparent conducting oxide that combines electrical conductivity with optical transparency, ideal for such films.

Calcium carbonate and silica are non-conductive fillers/glass materials, unsuitable for the conductive layer.