**Core Concept**
The question is testing the knowledge of vitamin A requirements in infants, which is a critical aspect of pediatric nutrition and public health. Vitamin A is an essential nutrient that plays a vital role in maintaining healthy vision, immune function, and skin integrity.

**Why the Correct Answer is Right**
The correct answer is 350 μg (micrograms), not milligrams (mg). The World Health Organization (WHO) recommends a daily intake of 350 μg of vitamin A for infants aged 0-6 months. This requirement is crucial for supporting the growth and development of the infant's immune system and preventing vitamin A deficiency, which can lead to night blindness, impaired immune function, and increased risk of infections. The recommended dietary allowance (RDA) for vitamin A in infants is based on the amount of retinol (the active form of vitamin A) required for optimal health.

**Why Each Wrong Option is Incorrect**
**Option B:** 600 μg is higher than the recommended daily intake for infants, but it is still not the correct answer. This option may be considered too high for infants, as excessive intake of vitamin A can be toxic.
**Option C:** 800 μg is also higher than the recommended daily intake and may be associated with adverse effects. This option is not a suitable answer for infants.
**Option D:** 1000 mg is an extremely high dose of vitamin A, far exceeding the recommended daily intake for infants. This option is incorrect and may be associated with serious health risks, including liver damage and birth defects.

**Clinical Pearl / High-Yield Fact**
It is essential for healthcare providers to be aware of the recommended dietary allowances for infants to prevent vitamin A deficiency and ensure optimal growth and development.

**✓ Correct Answer: A. 350 μg**