## Core Concept
The recommended daily intake of iodine varies across different life stages, with increased requirements during pregnancy and lactation due to the crucial role of iodine in fetal and infant thyroid function and brain development. Iodine is essential for the synthesis of thyroid hormones, which are vital for growth and development.

## Why the Correct Answer is Right
During pregnancy and lactation, the demand for iodine increases significantly. The World Health Organization (WHO) and other health institutions recommend that pregnant and lactating women consume 250 micrograms (mcg) of iodine per day. This increased requirement supports the production of thyroid hormones in both the mother and the fetus or infant, ensuring proper neurological and physical development. The correct answer reflects this elevated requirement.

## Why Each Wrong Option is Incorrect
**Option A:** 100 mcg - This is the recommended daily intake for non-pregnant adults, not for pregnant or lactating women. It does not meet the increased demand during these critical periods.

**Option B:** 150 mcg - This is the general recommended daily intake for adults but does not account for the increased needs during pregnancy and lactation.

**Option D:** 500 mcg - While higher intakes are sometimes recommended for certain conditions or populations, 500 mcg is above the generally recommended upper limit for pregnant and lactating women and could potentially lead to thyroid dysfunction.

## Clinical Pearl / High-Yield Fact
A key point to remember is that iodine deficiency during pregnancy and lactation can lead to severe consequences, including cretinism, miscarriage, and stillbirth. Pregnant and lactating women should ensure they meet the increased iodine requirement to support their health and the health of their child.

## Correct Answer: C. 250 mcg.