Which term describes a substance or material that cannot be penetrated?

• A. Impervious
• B. Imply
• C. Incidence
• D. Infection

Answer: (A)

Permeability is about whether something can pass through a material. A material that cannot be penetrated is impervious, meaning it blocks passage completely to liquids or gases under typical conditions. This describes a nonporous, sealed barrier—like a waterproof coat or a solid plastic membrane that stops water or air from getting through. The other terms don’t describe a barrier to penetration: to imply means to suggest something indirectly, incidence refers to how often something occurs, and infection is the invasion of pathogens. So impervious is the best fit.