**Core Concept**
Iodine is an essential micronutrient required for thyroid hormone synthesis. The recommended daily dose of iodine varies by age group to ensure adequate thyroid function and prevent iodine deficiency disorders.

**Why the Correct Answer is Right**
The recommended daily dose of iodine in children is based on the estimated average requirement (EAR) for thyroid hormone production. Iodine is absorbed in the small intestine and transported to the thyroid gland, where it is used to synthesize triiodothyronine (T3) and thyroxine (T4). Adequate iodine intake is crucial for growth and development, particularly in children. The World Health Organization recommends a daily iodine intake of 90 mcg for children aged 1-8 years.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is too low for children. Iodine deficiency can cause goiter, hypothyroidism, and cretinism.
**Option B:** This option is incorrect because it is too high for children. Excessive iodine intake can cause thyroid dysfunction, including hyperthyroidism.
**Option C:** This option is incorrect because it is not specific to children. Iodine requirements vary by age group.

**Clinical Pearl / High-Yield Fact**
Remember that iodine deficiency is a significant public health concern in many parts of the world, particularly in regions with limited access to iodized salt. Iodized salt is a simple and effective way to prevent iodine deficiency disorders.

**Correct Answer: D. 90 mcg**