Assertion: Silver bromide is used in photography.
Reason: Silver bromide is used in photography because silver bromide is photosensitive. It decomposes and is converted into metallic silver grains when light is incident on it.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both assertion and Reason are correct but Reason is not the correct explanation for Assertion.
C. Assertion is correct but reason is incorrect.
D. Both Assertion and Reason are incorrect.

Hint: Silver bromide is an alkyl halide. It is a pale-yellow, water-insoluble salt. Silver bromide is a light sensitive compound. This property is observed due to the deviations from ideal crystal structure.

Complete answer:
Silver bromide is a crystalline salt. It is represented as $AgBr$ . It has a fcc(face centered cubic) type of lattice structure.
Silver bromide is a pale-yellow colored water insoluble salt. It is very sensitive to light. Because of the sensitivity to light, it is used in photography.
For the chemical development of photographs, an emulsion using silver bromide is prepared. It is generally made on cellulose acetate with the help of gelatin. Gelatin increases the sensitivity of emulsion. This emulsion is poured on the film to create a latent image .
Due to the light, the silver bromide grains are reduced to metallic silver and a photographic image is created from the film. Now this image needs to be developed. The remaining silver bromide that is not reduced to metallic silver is washed away.
A negative film is generated from the photographic image. Silver bromide helps to form the latent image from the photographic film.
So assertion and reason are correct and reason is the correct explanation for assertion.
So, the correct answer is “Option A”.

Note:
Light sensitive compounds can be excited with the help of light or other source of energy. Silver bromide is used in photography because of the deviations in its crystal lattice structure. Silver bromide occurs naturally in mineral form but it can also be prepared from silver nitrate and an alkali bromide ( potassium bromide) .