Why did industry's in texas grow after the Cilver war?

After the Civil War, the railroad companies revolutionized the lumber industry. They needed great quantities of lumber to use for railroad ties, fuel, and other purposes. The railroads also connected the forests with the growing U.S. lumber markets. By the late 1800s lumber had become Texas's leading industry.

increases in demand are shown by a shift to the right in the demand curve. this could be caused by a number of factors, including a rise in income, a rise in the price of a substitute or a fall in the price of a complement.

which the answer is:

b