Final answer:
The correct practice for the safe use of tube holders and needles is to discard them both as a unit into a sharps container to prevent needle-stick injuries and maintain sterility.
Step-by-step explanation:
The correct statement regarding the safe use of tube holders and needles is: B. Discard both the needle and tube holder as a unit into a sharps container. After use, it's important to avoid disassembling the needle from the tube holder to prevent needle-stick injuries. The needle and the tube holder should be discarded as a single unit directly into a designated sharps container to ensure safety and maintain an aseptic environment.
Furthermore, tube holders and needles should not be cleaned for reuse as they are single-use items in medical and laboratory settings. Proper disposal and techniques for aseptic handling are crucial to prevent contamination and maintain sterility in procedures involving the transfer of liquids in a laboratory.