Which of the Following Is True About the Unions' Supply

Which of the following is true about the unions' supply curve of labor?

A) It shifts to the right because unions force firms to increase their employment.
B) It is horizontal at the wage rate established by the union.
C) Is the same as the marginal labor cost curve of the monopsonist.
D) It is steeper than a nonunion supply curve of labor.
E) It is downward sloping.