**Core Concept**
Breast milk production is a complex process regulated by hormonal influences, particularly prolactin and oxytocin. The average daily breast milk output is influenced by factors such as maternal nutrition, hydration, and the frequency and effectiveness of milk removal.

**Why the Correct Answer is Right**
The correct answer is 780 ml, which is the average daily breast milk output during the first 6 months of lactation. This output is influenced by the hormone prolactin, which stimulates milk production and secretion. Additionally, the hormone oxytocin plays a crucial role in milk ejection and letdown reflex. The breast milk output increases during the first few weeks after delivery and then stabilizes around 6 months.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is significantly lower than the average daily breast milk output during the first 6 months.
**Option B:** This option is incorrect because it is higher than the average daily breast milk output and may not be sustainable for the mother.
**Option C:** This option is incorrect because it is not a commonly cited estimate of average daily breast milk output during the first 6 months.

**Clinical Pearl / High-Yield Fact**
It's essential for lactating mothers to maintain adequate hydration and nutrition to support breast milk production. Additionally, frequent and effective milk removal is crucial to prevent engorgement and promote a healthy milk supply.

**Correct Answer:** B. 800 ml