The Figures Given Below Show the Demand (D)and Supply (S)

The figures given below show the demand (D) and supply (S) curves of labor in two different markets. Figure 15.3
-Which of the following is a reason for the wage differential shown in Figure 15.3?

A) The workers in Market B are more productive than the workers in Market A.
B) The workers in Market B are unionized whereas the workers in Market A are not.
C) Market B hires a larger number of skilled workers than Market A.
D) Market A represents the market for a risky occupation.
E) Working conditions offered by the firms in Market B are uncongenial.