Which of the following resources is renewable?

Step 1: Analyze the question The question asks which resource is renewable. A renewable resource can be replaced by natural processes within a reasonably short time (human lifetime), so it will not run out if used wisely.

Step 2: Explain the concept

• Renewable resources: can be replenished naturally. Examples are trees (forests), water, sunlight, wind, fish, and crops.
• Non-renewable resources: exist in limited amounts or take millions of years to form. Examples are fossil fuels (petroleum, coal, natural gas) and minerals/metals (iron, tin, gold).

Step 3: Examine each option

• A. Petroleum: a fossil fuel formed from the remains of organisms over millions of years. It is non-renewable.
• B. Coal: also a fossil fuel formed over millions of years. It is non-renewable.
• C. Iron: a metal ore mined from the earth's crust. Once mined, it is not replaced naturally. It is non-renewable.
• D. Trees: they can be replanted and regrow within years or decades. They are renewable.

Step 4: Answer The correct option is D. Trees.

Exam tip: Ask yourself, "Can nature or we replace it quickly?" Living things (trees, fish, crops) are generally renewable. Things dug from the ground (coal, petroleum, minerals) are non-renewable. Remember: "Dig it up = runs out; grow it back = renewable." Note that trees are only truly renewable if we replant them, which is why afforestation is important.