Which United Nations specification is designed to keep hazardous materials contained?

The correct choice is the performance-oriented packaging (POP) because it focuses on achieving performance goals for the packaging of hazardous materials. This specification is essential in ensuring that hazardous materials are contained and not released into the environment during transport. POP is based on testing methods that evaluate how well the packaging can withstand conditions it may encounter during handling and transportation, such as impacts, pressure, or temperature variations.

By emphasizing performance rather than just compliance with design specifications, the POP allows for innovative packaging solutions that still meet safety regulations. This approach ensures a higher level of safety and containment for hazardous materials, ultimately protecting public health and the environment.

The other options tend to emphasize either regulatory aspects, which may not inherently define the containment performance, or packaging that does not specifically address the particular challenges associated with hazardous materials.