What distinguishes renewable resources from non-renewable resources, and why is this distinction important for sustainability in case studies?

• A. Renewable resources replenish naturally on human timescales; non-renewables are finite.
• B. Renewable resources are always abundant; non-renewables are scarce.
• C. Renewable resources require less energy to extract; non-renewables require more energy.
• D. Renewable resources never pollute; non-renewables always pollute.

Answer: (A)