**Core Concept**
Exclusive breastfeeding refers to the practice of providing an infant with breast milk as the sole source of nutrition, without any additional foods or liquids, for a specific period. This practice has been shown to have numerous health benefits for both the mother and the infant.

**Why the Correct Answer is Right**
Exclusive breastfeeding is recommended by the World Health Organization (WHO) until at least 6 months of age. This is because breast milk provides the optimal mix of proteins, fats, carbohydrates, vitamins, and minerals that support the infant's growth and development. Additionally, breast milk contains antibodies that help protect the infant from infections and diseases. The American Academy of Pediatrics (AAP) also recommends exclusive breastfeeding for the first 6 months, and continued breastfeeding as complementary foods are introduced, for up to 12-24 months or longer as mutually desired by mother and infant.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is unlikely to be correct as exclusive breastfeeding is not recommended for a short period of time such as 1 month.
**Option C:** This option may seem plausible but the recommendation for exclusive breastfeeding is not based on the mother's age, but rather on the infant's age and developmental needs.

**Clinical Pearl / High-Yield Fact**
Infants who are exclusively breastfed have a lower risk of respiratory tract infections, ear infections, and diarrhea compared to formula-fed infants. Additionally, breastfeeding has been shown to have long-term health benefits, including a lower risk of obesity, type 2 diabetes, and certain types of cancer.

**Correct Answer:** D. 6 months.