Which of the following is considered a diagnostic supply?

Catheters are considered a diagnostic supply because they are primarily used to facilitate diagnostic procedures, such as accessing blood vessels for imaging studies or obtaining samples for analysis. They play a critical role in various diagnostic imaging techniques, including angiography, where they help visualize blood vessels to assess conditions such as blockages or abnormalities.

In contrast, balloons and stents are typically classified as therapeutic devices used in interventional procedures to treat conditions such as stenosis or occlusion. Embolization materials are utilized in procedures specifically aimed at blocking blood flow to a targeted area, often for treatment purposes and not for diagnosis. Thus, catheters stand out as vital tools in the diagnostic arsenal, making them the correct choice in this context.