What causes a blurred image in x-ray exposure?

A blurred image in x-ray exposure is primarily caused by patient movement or collimator movement. When a patient moves during the exposure, even slightly, it can lead to a double image or a smear effect on the resulting x-ray film, which results in a lack of clarity. Similarly, if the collimator (the device that narrows the beam of x-rays) moves or is improperly aligned, it can alter the focus of the x-ray beam, creating a blurred image. Both factors disrupt the precision required in capturing a sharp image of the dental structures.

The other options, while they pertain to x-ray processing, do not directly cause blurring in the same manner. Excessive light exposure before the x-ray could result in overexposure on film, leading to a dark image, but it wouldn't cause blurring. Incorrect developer temperature affects the chemical reactions during the developing process and could lead to inadequate image development, but again, that does not directly cause blurring. Lastly, inserting film into fixer before developing would result in the film being permanently damaged and not show any image at all, rather than creating a blurred image.