Gross Decontamination is defined as

• A. The initial phase of the decontamination process during which the amount of surface contaminant is significantly reduced as soon as possible.
• B. The planned and systematic process of reducing contamination to a level that is as low as reasonably achievable.
• C. The act of redirecting a liquid flow from an endangered area to a safe area.
• D. The rapid removal of contaminants from large numbers of victims in the fastest time possible.

Answer: (A)

Gross decontamination is the initial, rapid removal of surface contamination to lower exposure as quickly as possible, using simple, readily available methods at the scene. It aims to remove the majority of the contaminant right away—think removing contaminated clothing, brushing off surface material, and a quick wash—to prevent further transfer and to make later, more thorough decon safer and more effective.

The other descriptions refer to concepts outside this immediate, rapid surface-cleaning step: a general safety goal of minimizing exposure (ALARA) in broader contexts; redirecting liquid flow as a containment action; and rapid decon with large numbers of victims (mass decontamination) which addresses throughput rather than the specific initial reduction of surface contamination.