The table below gives total output of an employee of XYZ Corporation, which produces the ever-popular Whatzit. The "Total output" column tells you the running total of Whatzit's produced throughout the day.

Hours worked per day Total output

5 60

6 75

7 88

8 100

9 108

10 113

Refer to the table above:

Which of the following statements is true about this employee's Whatzit productivity?

Select one:

a. Total output is increasing through 10 hours of work, but marginal output decreases after the 6th hour.

b. Total output and marginal output are both increasing through 10 hours of work.

c. Marginal output exceeds total output for hours 6 through 10.

d. Total output is positive but marginal output is negative.