**Core Concept**
Breast milk composition is crucial for infant nutrition and growth. The water content of breast milk is a key determinant of its caloric density and nutrient solubility.

**Why the Correct Answer is Right**
Breast milk typically has a water content of approximately 87%. This high water content allows for optimal solubilization and absorption of nutrients by the infant. The lactose in breast milk also plays a crucial role in maintaining water balance and promoting the growth of beneficial gut flora. The water content of breast milk is carefully regulated by the hypothalamic-pituitary-adrenal axis, ensuring that it remains within a narrow range to meet the infant's nutritional needs.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the water content of breast milk is not around 80%. A lower water content would result in a more concentrated milk, which could lead to dehydration in the infant.
**Option B:** This option is incorrect because the water content of breast milk is not around 95%. A water content this high would result in a very dilute milk, which could lead to inadequate nutrient delivery to the infant.
**Option C:** This option is incorrect because the water content of breast milk is not around 70%. A lower water content would result in a more concentrated milk, which could lead to dehydration in the infant.

**Clinical Pearl / High-Yield Fact**
It's essential to note that breast milk composition can vary depending on factors such as the mother's diet, hydration status, and lactation stage. However, the general range of water content in breast milk remains relatively consistent across different populations.

**Correct Answer: C. 87%**