What photographic process relies on the formation of silver and a ferrous/ferric redox couple for fingerprint imaging?

The correct choice is the process that typically involves the formation of a ferrous/ferric redox couple, which is essential in the development of latent fingerprints. This method primarily relies on the use of metallic silver, where the latent prints that have been treated with a specific chemical solution can react to form visible images.

In this context, the physical developer is particularly effective because it enhances the visibility of fingerprints left on non-porous surfaces. It uses a reducing agent, which transforms ferric ions into ferrous ions during the development process, resulting in a clear representation of the fingerprints on a photographic medium. This is distinct from methods that do not use a redox reaction involving silver, focusing instead on digital or purely chemical methods without the same complex interactions between iron compounds.

By utilizing the principles of redox reactions to facilitate the visualization of latent prints, the physical developer effectively showcases latent fingerprint patterns that would otherwise remain unseen, thereby playing a crucial role in forensic science.