Which is an example of a change in productivity that increases labor demand? A) Mail-order catalog sales rise, thus increasing the demand for workers in the mail-order business. B) Sport utility vehicles increase in popularity, thus increasing the demand for the workers who make them. C) A decrease in the price of lumber decreases the cost of building homes, thus increasing the demand for construction workers. D) A technological change increases output per worker in the computer industry, thus increasing the demand for computer workers.