What is one of the three basic liquids required for processing photographs?

The three basic liquids essential for processing photographs are developer, fixer, and stop bath. The developer is responsible for converting the exposed silver halides in the photographic emulsion into metallic silver, which forms the image. The fixer then removes any unexposed silver halides, ensuring that the image is stable and not sensitive to light anymore. The stop bath is used to halt the development process quickly.

The correct liquid, which is crucial in the photographic development process, is the developer. This liquid initiates the creation of the image by allowing the exposed areas of the film or paper to become visible. Without the developer, photographic images would not form properly. The option mentioned in the question focuses on the specific necessity and function of these liquids in the overall process of photographic development. Understanding the role of each liquid clarifies the essential components involved in developing quality photographs.