21. (p. 188) The differences in climatic conditions among a firm's markets have limited impact on its product mix.
22. (p. 192) Plants already exist that produce crude oil from tar sand and shale.
23. (p. 192) There is a South African firm that produces gasoline, diesel fuel, and jet fuel from coal.
24. (p. 195) Currently, solar energy and other renewable energy sources are widely used.
25. (p. 195) Wind-generated power is the largest component of the U.S. power grid.
26. (p. 197) Nearly all of the world's chrome, manganese, and platinum are produced by South Africa and Russia.
27. (p. 198) The concept of sustainability has a narrow scope.
28. (p. 197) We have learned that the ocean floors contain vast amounts of strategic non-fuel deposits in structures known as black smokers.
29. (p. 198) China holds most of the world's gold deposits and lacks tin and tungsten.
30. (p. 190) Petroleum is a cheap source of energy.