In radiographic testing, an increase in source size generally leads to what effect on the image?

In radiographic testing, an increase in source size affects the sharpness of the image produced. When the size of the radiation source is larger, it leads to a phenomenon known as penumbra, which is the partial shadow around the edges of an object. This increased penumbra results in a decrease in clarity and sharpness of the radiographic image. The edges of the image become less defined, making it more challenging to discern fine details.

Conversely, if the source size were smaller, the image would generally be sharper, as there would be less penumbra effect, resulting in a clearer depiction of the object's features. Thus, an increase in source size is directly linked to a decrease in the clarity of the radiographic image, which supports the correctness of the selected answer.