## **Core Concept**
Visual acuity is a measure of the sharpness of vision, usually expressed as a fraction where the top number refers to the distance (in meters) at which a person with normal vision can read the same line on the Snellen chart, and the bottom number refers to the distance at which the person being tested can read it. A visual acuity of 6/6 indicates normal vision.

## **Why the Correct Answer is Right**
To determine at what distance the person can read a 6/24 line, we need to understand the relationship between the visual acuity and the distance at which the chart is read. If a person has 6/6 vision, they can read the 6/6 line at 6 meters. The 6/24 line is a larger line that a person with normal vision (6/6) can read at 24 meters. Since the person in question has 6/6 vision, they can read the 6/24 line at 24 meters because that is the distance at which a person with 6/6 vision can read the 6/24 line.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option suggests a distance of 6 meters, which is the distance at which a person with 6/6 vision can read the 6/6 line, not the 6/24 line.
- **Option B:** This option suggests a distance proportional to the visual acuity fraction given (6 meters * 24 / 6 = 24 meters), which matches our calculation for reading the 6/24 line.
- **Option C and D:** These are incorrect based on the proportional relationship not being correctly applied or being irrelevant to the direct calculation.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that visual acuity is inversely related to the size of the line on the Snellen chart that can be read at a given distance. A person with 6/6 vision can read lines that a person with normal vision can read at the same distance. For lines that are larger (like 6/24), a person with 6/6 vision can read them at a farther distance, specifically 24 meters in this case.

## **Correct Answer:** .