Which tool is described as an x-ray film holding device?

The tool referred to as an x-ray film holding device is the Snap A-Ray. This instrument is specifically designed to securely hold x-ray films in place during radiographic procedures, allowing the dental professional to take accurate and clear images of the patient's teeth and jaws without needing the patient to hold the film. This promotes better image quality and minimizes the risk of motion blur.

The Snap A-Ray features a design that accommodates different film sizes and allows for easy placement in the patient's mouth. Its use is crucial in ensuring that the films are positioned correctly relative to the x-ray source, which is vital for obtaining diagnostic quality radiographs.

In distinguishing this tool from others listed, the X-ray View Box is a device used to view developed x-ray films rather than hold them in place, the X-ray Developer is a solution used in the process of developing the films themselves, and the Bridge Threader is an instrument unrelated to x-rays, as it is designed for use in dental procedures involving bridges and prosthetics. Therefore, the Snap A-Ray stands out as the correct answer for an x-ray film holding device in this context.