## Core Concept
The World Health Organization (WHO) recommends specific oral doses of vitamin A for children with vitamin A deficiency, based on their age and severity of deficiency. Vitamin A is crucial for vision, immune function, and skin integrity.

## Why the Correct Answer is Right
For children with vitamin A deficiency, the WHO recommends the following oral doses of vitamin A:
- 100,000 IU for children 1 year and older.
Given that the child in question is 2 years old and weighs 12 kg, the appropriate dose falls into this category.

## Why Each Wrong Option is Incorrect
- **Option A:** 10,000 IU is too low for a 2-year-old child and is typically recommended for infants under 6 months.
- **Option B:** 20,000 IU might be considered for younger children or less severe deficiencies but does not match the recommended dose for a 2-year-old.
- **Option D:** 200,000 IU is higher than the recommended dose for children over 1 year and could potentially lead to toxicity.

## Clinical Pearl / High-Yield Fact
A key point to remember is that vitamin A toxicity can occur with high doses, leading to symptoms like headache, vomiting, and increased intracranial pressure. The recommended dose for children over 1 year is 100,000 IU.

## Correct Answer Line
**Correct Answer: C. 100,000 IU.**