___ is the killing of all organisms.

• A. Filtration
• B. Cleaning
• C. Pasteurization
• D. Sterilization

Answer: (D)

Sterilization means killing all microorganisms, including resistant spores, so nothing viable remains. This level of destruction is achieved by methods that apply strong heat, chemical sterilants, irradiation, or certain filtration processes designed to inactivate every organism.

Other options don’t guarantee complete elimination. Filtration removes microbes by trapping them but doesn’t necessarily kill every organism that might pass through or survive treatment. Cleaning is about removing soil and reducing microbial load, not killing all organisms. Pasteurization uses moderate heat to lower numbers and destroy many pathogens, but some microbes and spores can survive, so it isn’t total sterilization.

So the term that describes killing all organisms is sterilization.