Use the Figure Below to Answer the Following Question

Use the figure below to answer the following question. Figure 18.3.4
-Refer to Figure 18.3.4.At an employment level of 30 hours per week,the compensation required for the cost of acquiring human capital is

A) $0.
B) $2 an hour.
C) $4 an hour.
D) $6 an hour.
E) cannot be determined without knowing the demand for labour.