The increasing costs of fossil fuels such as gas, coal, and oil due to the depleting resources of such fuels have prompted many to suggest bio-fuels as a cheaper and greener substitute for them.
While biofuels may be more environment-friendly, it is highly debatable whether such fuels will in fact present a significant cost advantage. For instance, many common crops used as resources for biofuels can be economically grown only in limited parts of the world;
in other regions the same crops would be impossible or extremely costly to grow.
In the argument given, the two boldfaced portions play which of the following roles?
A. The first is the position taken by the argument; the second provides evidence to support that position.
B. The first describes the circumstance that the argument as a whole seeks to establish; the second opposes that established position.
C. The first offers evidence that the argument does not dispute; the second exemplifies the conclusion.
D. The first is a claim that is called into question by the argument; the second provides a circumstance opposed by that claim.
E. The first states a possibility that the argument denies; the second is evidence that is accepted by the argument.