Private goods are those for which consumption is

In the market for cell phones, which of the following events increases the supply of cell phones?

A. New technology lowers the cost of making a cell phone B. Rise in the price of an e-book reader (a substitute in production) C. An increase in people's incomes D. A rise in the wage rate paid to electronics workers

A valid and useful theory of gold prices:

A) helps to predict the movements of gold prices over time. B) may be founded on simplifying assumptions. C) need not exactly predict every change in gold prices. D) all of the above E) none of the above