Labor unions may attempt to raise wage rates by:

A) increasing the supply of labor.
B) forcing employers,under the threat of a strike,to pay above-equilibrium wage rates.
C) decreasing the demand for labor.
D) increasing the price of complementary resources.

Labor unions typically negotiate with employers to increase wages above the equilibrium level by threatening to go on strike, which would disrupt the employer's business operations. This leverage puts pressure on the employer to pay higher wages to avoid the costs associated with a strike. Increasing the supply of labor would lower wages, decreasing the demand for labor would result in fewer jobs, and increasing the price of complementary resources would increase the cost of production and likely lower employment opportunities.