Radiological hazard sign is indicated by which color and lettering?

• A. Yellow sign with white letters
• B. Blue sign with white letters
• C. White sign with black letters
• D. White sign with red letters

Answer: (C)

The main idea is readability and clear communication of a warning. A radiological hazard sign uses black lettering on a white background because this combination provides the highest contrast, making the warning text easy to read quickly in various lighting conditions. The text message needs to be legible at a glance, so black on white is the most straightforward, universally understood format for warnings.

Other color and lettering combos are associated with different safety cues. Yellow backgrounds are for caution, blue indicates a mandatory action, and red signals immediate danger or prohibition. Those colors shift the emphasis away from the plain warning text itself, which is why white with black lettering is the most effective and appropriate for clearly conveying a radiological hazard.