Which of the following is a definition of Waste?

• A. A renewable energy source
• B. Outputs that include anything not useful or consumed, and non-useful products generated within the system
• C. Materials to be recycled
• D. A type of air pollutant

Answer: (B)

Waste is any output from a system that isn’t useful or isn’t consumed. In environmental management, a process can produce both useful products and by‑products that aren’t needed. All those unwanted or non‑useful outputs—whether solid, liquid, or gaseous—are considered waste because the system can’t use them in their current form.

Why this fits best: it captures the broad idea that waste isn’t just trash to throw away, but any non‑useful side effect of a production or consumption cycle. A renewable energy source is energy itself, not a waste product. Materials to be recycled are potential resources, not a definition of waste, since they describe future handling rather than current non‑usefulness. A pollutant is a specific type of harmful output, but waste encompasses all non‑useful outputs, not just pollutants.