What does 'Adequate light' mean in the D4 Vision item?

What does 'Adequate light' mean in the D4 Vision item?

• A. Very bright lighting improves accuracy.
• B. Adequate light — What is sufficient or comfortable for a person with normal vision.
• C. Dim lighting is adequate for near tasks.
• D. Any lighting is acceptable.

Answer: (B)

Adequate light means enough illumination for a person with normal vision to see and perform typical tasks comfortably. It’s about sufficiency, not extreme brightness or universal acceptability. In practice, it corresponds to lighting that is sufficient or comfortable for someone with normal vision to see details and read or recognize things without strain or glare. That’s why the description stating it as what is sufficient or comfortable for normal vision is the best fit. Very bright lighting isn’t required and can cause glare, dim lighting may be too weak for near tasks, and any lighting level isn’t automatically acceptable because some levels hinder visibility.

Adequate light means enough illumination for a person with normal vision to see and perform typical tasks comfortably. It’s about sufficiency, not extreme brightness or universal acceptability. In practice, it corresponds to lighting that is sufficient or comfortable for someone with normal vision to see details and read or recognize things without strain or glare. That’s why the description stating it as what is sufficient or comfortable for normal vision is the best fit. Very bright lighting isn’t required and can cause glare, dim lighting may be too weak for near tasks, and any lighting level isn’t automatically acceptable because some levels hinder visibility.