Final answer:
Breast-fed infants primarily have Bifidobacterium species in their intestinal flora, which are beneficial and encouraged by the growth factors in breast milk. These bacteria aid in digestion, and immune response, and are also used in probiotics and yogurt production. The answer is option C.
Step-by-step explanation:
The intestinal flora of breast-fed infants consists primarily of Bifidobacterium species whose growth is favored by the growth factor from breast milk. Unlike adults, who have diverse gastrointestinal tract flora, infants receive their initial beneficial bacteria from birth and breastfeeding.
These Bifidobacterium spp. are important for the development of the infant's gut microbiota and provide health benefits such as aiding digestion and priming the immune system. The bacteria are filamentous anaerobes that are a substantial part of the human gut microbiota and are frequently used as probiotics and in yogurt production. Moreover, the gut microbiome of infants continues to change and evolve, especially during the first years of life.