**Core Concept**
Folic acid is a crucial water-soluble vitamin for various bodily functions, including DNA synthesis, repair, and methylation. During lactation, the requirement for folic acid increases due to its role in fetal development and maternal health.

**Why the Correct Answer is Right**
The correct answer reflects the increased demand for folic acid during lactation to support fetal growth and development, as well as maternal health. Folic acid is essential for the production of red blood cells, and its deficiency can lead to megaloblastic anemia. The recommended daily intake of folic acid is higher during lactation to ensure adequate supply to both the mother and the infant.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is too low and does not account for the increased demand during lactation.
**Option B:** This option might be close, but it does not accurately reflect the recommended increase in folic acid requirement during lactation.
**Option D:** This option is also incorrect, as the recommended daily intake of folic acid during lactation is higher than the standard recommendation.

**Clinical Pearl / High-Yield Fact**
A pregnant or lactating woman with a history of folic acid deficiency should receive a higher dose of folic acid supplementation to prevent megaloblastic anemia and ensure fetal development.

**Correct Answer: A. 400 mcg.**