## **Core Concept**
The World Health Organization (WHO) has defined specific criteria for visual impairment and blindness to facilitate global comparisons and screenings. Visual acuity is a critical measure used in these definitions. The classification helps in identifying individuals who require medical intervention or assistance.

## **Why the Correct Answer is Right**
The correct answer, **3 meters**, is based on the WHO's definition of blindness. According to the WHO, blindness is defined as a visual acuity of less than 3/60 or counting fingers at a distance of 3 meters in the better eye with the best possible correction. This definition serves as a standard for public health and clinical assessments globally.

## **Why Each Wrong Option is Incorrect**
- **Option A: 1 meter** - This distance is too short and does not align with the WHO's definition of blindness. It might be used in other assessments but not for the definition of blindness.
- **Option B: 5 meters** - This distance is farther than what is defined by the WHO for blindness. While visual acuity tests can be performed at various distances, 5 meters is not the specified distance for defining blindness.
- **Option D: 6 meters** - Similar to option B, 6 meters is also not the distance used in the WHO's definition of blindness.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the ability to count fingers at 3 meters is a critical and simple test for assessing visual acuity in a clinical setting, especially in resource-limited areas. This method is quick and can help identify individuals with severe visual impairment or blindness who may require further evaluation or intervention.

## **Correct Answer: C. 3 meters**