Which of the following experiments will yield observations that would allow one to calculate the marginal physical product of labor?
a.Increase the number of lumberjacks with chain saws and observe the change in output of cut trees
b.Increase the number of workers on an assembly line and record the change in output
c.Increase the number of data entry operators and computers and calculate the extra output
d.Check the number of workers before and after a given time period.