Final answer:
Giving complex carbohydrates from breast milk to microbiota promotes the growth of beneficial bacteria.
Step-by-step explanation:
The effect of giving complex carbohydrates from breast milk to microbiota is that it promotes the growth of beneficial bacteria. Breast milk contains complex carbohydrates called human milk oligosaccharides (HMOs), which cannot be digested by the baby but serve as a food source for the beneficial bacteria in the baby's gut. These bacteria then produce short-chain fatty acids (SCFAs) that provide energy for the baby and have various health benefits.