18. $200 This is used to manufacture products, to transport goods and people, and to supply our heating, cooling, and lighting needs. Some sources can be limited (coal, oil, gas, etc.) or unlimited (solar, wind, geothermal, etc.)
20. $300 This resource includes air, timber, water, land, minerals, plants and animals. There are two types of natural resources non-renewable and renewable. Non-renewable cannot be grown or replaced.