Which of the following is a common source of probiotics?

Yogurt is a common source of probiotics due to its fermentation process, which involves specific strains of bacteria that are beneficial for gut health. These live cultures, which include Lactobacillus and Bifidobacterium species, are added to milk during the fermentation process, turning it into yogurt. This rich presence of live microorganisms is what makes yogurt a prominent food choice for individuals looking to enhance their gut microbiome and overall digestive health.

In contrast, while milk can contain probiotics when certain cultures are added, it does not inherently provide probiotics in the same way yogurt does. Cheese may also contain some probiotics depending on the type and how it's made, but many cheeses lack live cultures because the aging process can kill off the beneficial bacteria. Eggs, on the other hand, do not contain probiotics at all. Therefore, when identifying a common source of probiotics, yogurt stands out as the most direct and well-known option.