Direct visual examination is possible when the eye can be placed within

• A. 305 Mm (12 In.) From The Inspection Surface.
• B. 381 Mm (15 In.) From The Inspection Surface.
• C. 610 Mm (24 In.) From The Inspection Surface.
• D. 762 Mm (30 In.) From The Inspection Surface.

Answer: (C)

Direct visual examination relies on seeing surface features with the naked eye under good lighting, without any magnification. The ability to resolve defects depends on how close the eye can get to the surface—the nearer the eye, the larger the defect will appear to the eye. The practical limit for reliable direct vision is 610 mm (24 inches) from the inspection surface. Within this distance, flaws on the surface are detectable without instruments; beyond it, the eye cannot resolve small details reliably, so you would need magnification or another inspection method. The other distances are either closer (which would still work) or farther than the maximum recommended distance (30 inches), which would not allow direct visual inspection.