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 is facing MRP1,a wage rate of $12 per hour and is employing 150 units of labour.At this level of employment,

A) the last unit of labour is adding less to the firmʹs cost than it is adding to the firmʹs revenue,so it should increase the use of labour.
B) the last unit of labour contributes as much to the firmʹs costs as to the firmʹs revenues and so the firm should not change its use of labour.
C) the last unit of labour is adding more to the firmʹs cost than it is adding to the firmʹs revenue,so it should reduce the use of labour.
D) the firm has shifted the MRP curve to MRP2.
E) the firm has shifted the MRP curve to MRP3.