Which of the Following Union Tactics, If Successful, Would Increase

Which of the following union tactics, if successful, would increase wages and create a surplus of labor?

A) collective bargaining to fix the wage above the competitive level
B) decreasing the marginal revenue product of the union workers
C) increasing the demand for union-made products
D) restricting the supply of nonunion products that compete with union-made products
E) increasing labor productivity by minimizing conflicts and resolving differences between labor and management