Which of the following is NOT a type of nuclear material?

The correct choice identifies "chemical materials" as not being classified as nuclear materials. Nuclear materials specifically refer to substances that are used or produced in nuclear reactions, which includes types like special nuclear materials (such as plutonium or highly enriched uranium), and industrial or medical materials that may be used for applications involving radioactive isotopes, like radiography or cancer treatment.

In contrast, chemical materials are typically involved in chemical reactions and are not associated with nuclear reactions or properties. Thus, while special nuclear, industrial, and medical materials can all be linked to processes or applications involving nuclear reactions or radioactivity, chemical materials do not belong to that category. This distinction is essential for understanding the specific classifications of materials relevant to nuclear science and regulatory frameworks.