Which of the following is a requirement for routine specimen packaging?

Triple packaging is essential for routine specimen packaging to ensure the safety and integrity of the contents during transport. This method involves using three layers of protection: an inner leak-proof container holding the specimen, this container is placed within an absorbent material that can soak up any spills, and an outer durable transportation container that provides additional protection. This structure is designed to prevent any leakage that could occur if the inner container were to break, thereby protecting carriers, the environment, and the public from exposure to potentially infectious materials.

The other options do not offer the same level of safety or compliance with regulations for transporting dangerous goods. Single packaging, for instance, lacks the necessary protection against leakage, while using secondary containment alone does not offer the robust safeguard of triple packaging. Additionally, labeling with "biological hazard" is important for communication but is part of the overall requirements rather than a stand-alone solution for safe transport. Thus, triple packaging aligns with safety regulations and best practices for the transport of specimens, making it the correct choice.