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.