A firm in short-run equilibrium always earns positive profits if

The use of seat belts and other automobile safety features making bicycling more hazardous can be explained by the economic concept known as

A) the principle of diminishing returns. B) the principle of voluntary exchange. C) the real-nominal principle. D) the marginal principle.

As oil prices increase, it becomes more economical to extract oil from sources like tar sands

Indicate whether the statement is true or false