Which condition leads to decreased image clarity in dental radiographs?

Decreased image clarity in dental radiographs is primarily caused by factors that affect the quality of the image captured. High patient movement during the exposure can lead to blurriness, as the radiographic image relies on a stable position to achieve a sharp representation of the dental structures. When a patient moves, even slightly, the X-ray beam may capture multiple positions of the teeth within a short period, resulting in a blurred image that obscures detail.

In contrast, low exposure time may lead to underexposure, but it does not inherently cause blurriness; rather, it affects the overall density of the image. Proper film storage is about preserving the integrity of the film until use and does not impact the clarity of an image during exposure. Similarly, correct alignment of the position-indicating device (PID) is crucial for accurate beam positioning and does not contribute to decreased clarity if properly executed. Therefore, the key factor leading to decreased image clarity in this scenario is the motion of the patient during the exposure process.