Which of the following is NOT listed as a type of contamination?

• A. Fixed contamination, surface contamination, and discrete radioactive particles
• B. Fixed contamination, loose contamination, and discrete radioactive particles
• C. Loose contamination, discrete radioactive particles, and surface contamination
• D. Internal contamination, fixed contamination, and loose contamination

Answer: (D)

The main idea here is understanding how contamination is categorized. In radiation safety, surface contamination is described using categories like fixed contamination (tightly bound and not easily removed), surface contamination (on a surface and removable), loose contamination (not fixed and easily transferable), and discrete radioactive particles (small contaminating particles). Internal contamination, on the other hand, refers to radionuclides that have entered the body and reside inside it, which is a different concept from surface contamination categories.

Because internal contamination is not a surface-related contamination type, a set that includes internal contamination alongside surface types is not part of the standard list of contamination types. The option that includes internal contamination with fixed and loose contamination fits this scenario, making it the NOT-listed option.