Which of the following agents lowers water activity in food, making it less suitable for pathogenic growth?

The correct choice indicates that all the listed agents—salt, sugar, and freezing—are effective in lowering water activity in food, making conditions less favorable for the growth of pathogens.

When salt is added to food, it draws out moisture through the process of osmosis. This reduction in available water creates an environment that's hostile to many microorganisms that require water to grow, thereby acting as a preservative.

Sugar functions in a similar way; it also decreases water activity and can prevent microbial growth. High concentrations of sugar create a hypertonic environment, which inhibits the ability of pathogens to thrive as they lose water to the sugar solution.

Freezing lowers the temperature of food and reduces the kinetic energy of water molecules, effectively immobilizing them and reducing water availability for bacteria. While freezing does not eliminate pathogens, it prevents their growth during storage.

Understanding that all of these agents contribute to lowering water activity provides a foundation for food preservation methods and HACCP principles, emphasizing the importance of controlling microbial growth in food safety.