Final answer:
The essential step in the process of thawing frozen food is slow thawing. It is necessary to prevent bacterial growth and ensure food safety.
Step-by-step explanation:
An essential step in the process of thawing frozen food, also known as slacking, is b) Slow thawing. This method allows for the gradual increase in temperature, preventing the growth of bacteria which could proliferate in unsafe temperature zones. According to the USDA, safe thawing methods include in the refrigerator, in cold water which is changed every 30 minutes, or in the microwave. These methods are crucial to maintain food safety and ensure that once the food has thawed, it should be handled like fresh perishables.