Which of the following is true about the symbol requirement on letters used by registered transporters?

• A. The biological hazard symbol must be displayed on letters with a minimum diameter of 6 inches.
• B. The symbol is optional on letters.
• C. The symbol must be on letters with a minimum diameter of 2 inches.
• D. No symbol is required on letters.

Answer: (A)

The key idea is that the biohazard warning on letters used by registered transporters must be clearly visible and standardized in size. The symbol needs to be large enough to be noticed quickly, so the rule sets a minimum diameter of 6 inches. This ensures the warning remains legible during handling, sorting, and inspection, even from a distance or when the letter is placed among other materials. It also keeps labeling consistent with regulatory expectations, protecting workers and preventing mishandling of regulated medical waste. So the requirement is a 6-inch minimum diameter on those letters.