The correct answer is C. Latent image.
On an exposed dental radiographic film, the latent image refers to the invisible image that is formed after exposure to X-rays. This image is created by the differential absorption of X-rays by the structures within the mouth, such as teeth and bones. The latent image remains invisible until the film undergoes chemical processing procedures, which involve the use of developer and fixer solutions. These solutions chemically react with the exposed silver halide crystals on the film, causing the latent image to become visible.