Which of the Following Is Correct

Multiple Choice

Which of the following is correct?

A) In unionized industries,wages are above the level that would prevail in competitive markets.
B) The introduction of a union in some industry reduces the quantity of labor demanded in that industry,causes some workers in that industry to be unemployed,and reduces wages in the rest of the economy.
C) Critics argue that the allocation of labor resulting from unions is both inefficient and inequitable.
D) All of the above are correct.