Which of the following is a common use of probiotics?

The restoration of gut flora is a primary and well-established use of probiotics. Probiotics are live microorganisms that, when consumed in adequate amounts, provide health benefits, particularly for the digestive system. They help to restore the balance of beneficial bacteria in the gut, especially after disruptions caused by factors such as antibiotic use, illness, or poor diet. Maintaining a healthy gut flora is crucial for optimal digestion, immune function, and overall health.

In contrast, storage of food products and production of antibiotics are not primary applications of probiotics. While some microorganisms involved in fermentation can contribute to food preservation or even play a role in antibiotic production, these functions are not the main focus of probiotics. Alcohol fermentation pertains to the conversion of sugars into alcohol by yeast or bacteria, which is a different process than what probiotics typically engage in within the human gut. Thus, the most relevant and acknowledged role of probiotics among the listed choices is indeed the restoration of gut flora.