Which of the Following Decreases in Labor Demand Is Due

Which of the following decreases in labor demand is due to a change in product demand?

A) An increase in the price of paper increases the cost of making books, thus decreasing the demand for bookbinders.
B) The widespread availability of news on the web reduces the demand for newspaper workers.
C) An increase in the price of steel increases the cost of producing cars and trucks, thus decreasing the demand for automobile workers.
D) A decline in productivity in retailing decreases the demand for retail sales workers.