What principle in waste management emphasizes extracting useful materials from waste before it is sent to landfills?

The principle that emphasizes extracting useful materials from waste before it is sent to landfills is recovery. This concept involves techniques and processes that capture materials and energy from waste streams, allowing them to be utilized instead of being disposed of in landfills. Recovery can include both recycling and the extraction of energy, ensuring that valuable resources are not wasted and that the overall environmental impact of waste is minimized.

In contrast, the other options serve different roles in waste management. "Reduce" focuses on minimizing the amount of waste generated in the first place, while "reuse" refers to using items multiple times before discarding them, extending their lives and reducing the need for new products. "Recycle" specifically pertains to processing materials to create new products. While recycling is a significant aspect of recovery, the broader definition of recovery encompasses all methods of reclaiming useful materials and energy from waste.