The table above gives costs at Jan's Bike Shop. Unfortunately, Jan's record keeping has been spotty. Each worker is paid $100 a day. Labor costs are the only variable costs of production. What is the total variable cost of producing 60 bikes?

Answer the following statements true (T) or false (F)

1) U.S. immigrants (legal and illegal combined) have lower prison rates than the native-born population. 2) Illegal immigration has little effect on the average level of wages in the United States. 3) Economic theory suggests that immigration should be allowed into a country until the marginal benefit of the last immigrant is zero. 4) The optimal level of immigration occurs where marginal benefit is at its greatest.

When marginal utility is zero, total utility

A. is zero. B. is maximized. C. is falling. D. is negative.