The Diagram Below Shows the MRP Curve for a Firm

Multiple Choice

The diagram below shows the MRP curve for a firm producing copper plumbing pipe.The factor of production being considered here is hours of labour. FIGURE 13-1
-Refer to Figure 13-1.Suppose this firm initially has the marginal revenue product curve MRP₁.One reason that the curve could shift to MRP₃ is

A) an increase in demand for the firm's output,copper plumbing pipe.
B) a decrease in the market price of copper plumbing pipe.
C) a decrease in the supply of labour.
D) an increase in the wage rate.
E) an increase in the marginal product of labour.