During which phase of film processing do chemicals convert exposed silver halide grains to black/silver, making the image visible?

The correct choice highlights the crucial phase in film processing known as developing. During this stage, the film is immersed in a developing solution, typically containing reducing agents and chemicals that react with the exposed silver halide grains. The exposed grains, which have been made sensitive to light, undergo a chemical reduction process where they are converted into black metallic silver, forming the visible image on the film.

This conversion is fundamental to photographic processing, as it transforms the latent image—created during exposure to light—into a developed image that can be seen. The developing solution works selectively, only affecting the areas that were exposed to light, thus preserving the unexposed areas of the film, which are later removed during the fixing phase.

The other options represent different stages in the film processing workflow. The exposing phase involves the initial capture of the image, while the fixing phase is responsible for halting the development process by removing unexposed silver halide grains. The drying phase follows processing, allowing the film to dry completely and making it ready for handling. Each step is important, but developing is specifically where the image becomes visible through the chemical conversion of silver halides to silver.