The concept of "opportunity cost" helps us explain the choices of

Economic theory assumes elected and appointed government officials

A) place their personal or private welfare ahead of the public interest. B) place the public interest ahead of any personal or private interests of their own. C) are free to pursue the public interest because they aren't constrained by competition. D) respond to the anticipated costs and benefits to themselves of decisions contemplated.

Which of the following pairs of goods would be considered complementary?

a. Coca-Cola and Pepsi b. computers and computer software c. radios and televisions d. mass transit and private automobiles e. compact discs and cassette tapes