Final answer:
The sharpness of a radiographic image worsens when the Source-to-Object Distance is decreased due to a larger penumbra that reduces image detail and clarity.
Step-by-step explanation:
The sharpness of the radiographic image is deteriorated by decreasing the Source-to-Object Distance (SOD). When the SOD is decreased, the source of the radiation is closer to the object, which increases the potential for magnification error and reduces image sharpness. This is because a larger penumbra (blur) is created at the edges of structures within the image, leading to a loss of detail and a less sharp image.