Which of the following is an effect of using too much developer on a radiographic film?

Using too much developer on a radiographic film results in darkening of the image. This occurs because the developer's chemical activity is increased, leading to excessive reduction of the silver halide crystals in the emulsion layer of the film. When these crystals are overly reduced, they create a densified black area, resulting in a film that appears darker than intended.

The darkening effect can obscure details and nuances in the image, which is detrimental for diagnostic purposes. This is critical in radiography, where clarity and the accurate representation of anatomical structures are essential for proper evaluation and diagnosis.

In contrast, overexposure does not typically result from developer quantity but rather from the exposure to radiation or X-rays being too high. Underdevelopment is associated with insufficient time or an under-diluted developer rather than an excess of developer. Graininess is often a result of the film itself or processing conditions but isn't directly caused by overdeveloping through excessive developer usage. Thus, darkening from too much developer is the most relevant outcome regarding the options presented.