The Table Below Shows the Total Production for Varying Numbers

Multiple Choice

The table below shows the total production for varying numbers of hours worked producing yo-yos.The firm sells its product and hires its workers in competitive markets.
TABLE 13-4
-Refer to Table 13-4.Which of the following statements best describes the situation of this firm when it is employing 12 hours of labour? The 12th hour of labour hired

A) adds $10 to revenue and costs $10 to hire,so this firm is maximizing its profit at 12 hours of labour.
B) adds $5 to revenue,but costs $10 to hire,so this firm should hire less labour.
C) adds $30 to revenue,but only costs $10 to hire,so this firm should hire more labour.
D) adds $8 to revenue,but costs $10 to hire,so this firm should hire less labour.
E) adds $40 to revenue,but only costs $10 to hire,so this firm should hire more labour.