What is one way to reduce waste after the use of materials?

Promoting recycling of materials is a key method for reducing waste after the use of materials. When materials are recycled, they are processed and converted into new products instead of being discarded as waste. This process not only helps prevent materials from ending up in landfills, which can harm the environment, but it also conserves natural resources and reduces the need for raw material extraction. By recycling, we can significantly minimize the overall waste generated and contribute to a more sustainable cycle of production and consumption.

The other options, while they may have their merits in certain contexts, do not effectively address waste reduction. For instance, using items only once contributes to higher waste generation, selling off used materials does not necessarily ensure they are repurposed responsibly, and encouraging the purchase of more products can lead to increased waste and resource consumption rather than reducing it. Thus, recycling stands out as a practical and effective solution to manage material waste.