Silver halides are used in photographic plates because they are A. Oxidised in air B. Soluble in hyposolution C. Reduced by light D. Totally colourless

The correct answer is C. Silver halides are reduced by light.

When light hits a silver halide crystal, it causes an electron to be ejected from the silver atom. This electron is then captured by a neighboring silver atom, which

causes it to be reduced to silver metal. The silver metal then forms a black precipitate on the surface of the crystal. This is how photographic images are created.

The other options are incorrect. Option A is incorrect because silver halides are not oxidized in air. Option B is incorrect because silver halides are not soluble in hyposolution.

Option D is incorrect because silver halides are not totally colorless. Silver halides are actually white or gray in color.