What defines a nonrenewable resource?

• A. A resource that can be replaced.
• B. A resource that cannot be replaced.
• C. A resource that is unlimited.
• D. A resource that never depletes.

Answer: (B)

Nonrenewable resources are resources that cannot be replenished within a human lifetime because they form extremely slowly in nature. Once you extract and use them, new deposits won’t be available on timescales useful to us. That’s why the defining idea is that they cannot be replaced. Examples include fossil fuels and many metal ores. In contrast, renewable resources can be replenished relatively quickly, and the notions of being unlimited or never depleting don’t apply to nonrenewables.