**Core Concept**
The Vitamin A supplement administered in public health programs is a crucial component of preventive medicine, particularly in the context of childhood malnutrition and vitamin A deficiency. Vitamin A deficiency can lead to night blindness, impaired immune function, and increased risk of infections, making supplementation a vital intervention.

**Why the Correct Answer is Right**
The Vitamin A supplement administered in the "Prevention of nutritional blindness in children programme" typically contains 1 lakh IU (100,000 IU) per 100 ml of solution. This concentration is designed to provide a safe and effective dose of vitamin A to prevent vitamin A deficiency and associated health problems in children. The recommended dose is often tailored to the child's age and weight, ensuring that the supplement is neither too low nor too high.

**Why Each Wrong Option is Incorrect**
**Option A:** 25,000 IU/ml is too low to effectively prevent vitamin A deficiency in children, as it would not provide sufficient vitamin A to meet their daily needs.
**Option B:** 3 lakh IU/ml is excessively high and could potentially lead to toxicity, particularly if administered to younger children or in high doses.
**Option D:** 5 lakh IU/ml is also excessively high and would likely cause vitamin A toxicity, which can lead to adverse effects such as headaches, dizziness, and liver damage.

**Clinical Pearl / High-Yield Fact**
When administering vitamin A supplements, it is essential to note that high doses can cause toxicity, particularly in children. A safe and effective approach is to use the recommended dose of 1 lakh IU per 100 ml, which is tailored to the child's age and weight.

✓ Correct Answer: C. 1 lakh IU/ml