Disinfectants become inactivated when:

• A. They are diluted
• B. They become visibly contaminated
• C. They are stored in sunlight
• D. They are used correctly

Answer: (B)

Disinfectants lose their punch when there’s organic material in the mix. When a solution becomes visibly contaminated with dirt, blood, mucus, or other organic matter, those substances interact with the active chemical and consume or neutralize part of it. That chemical load prevents the disinfectant from reaching and destroying microbes effectively, so the product is considered inactivated. In practice, you should discard visibly dirty disinfectant and reprepare a fresh solution or pre-clean the surface first so disinfection can work. By contrast, simply diluting a disinfectant lowers its strength but isn’t the inactivation scenario described here, and storing in sunlight or using it correctly affect performance in different ways rather than indicating inactivation.