Answer: C - The level of water activity required for microbial growth is 0.85. Any level higher than this is considered an environment prone to bacterial growth. For this reason, it is important to treat all foods with water activities above this value as a potentially hazardous food.
Water activity (aw) is a measurement of the moisture content of a food, expressed as a ratio of the vapor pressure in the food item in a given condition vs. the vapor pressure of distilled water in the same condition. The amount of unbound H2O molecules present in a food generally correlates directly to the likelihood of microbial growth on the food, including yeasts, molds, and bacteria.
