Which term describes the shielding thickness?

• A. A continuous piece of metal surrounds the component to be hardened
• B. Video Indicator
• C. Detector Array
• D. A fraction of a millimeter

Answer: (D)

Shielding thickness is a physical dimension that describes how much material covers or separates something from radiation. The term here is pointing to the actual measurement itself, and a fraction of a millimeter conveys a small, precise thickness often used for thin shielding layers. This framing matters because the attenuation depends on both the material and how thick it is; describing it as a fraction of a millimeter clearly communicates the scale of the shield.

The other options describe what shielding is or related devices rather than the thickness: a continuous metal enclosure describes the shielding structure itself, while a video indicator or detector array refers to components, not the thickness of the shielding.