Hank Preston is the owner of Preston​ Mechanics, an​ auto-repair shop that does automobile servicing and repairs. Faced with an increasing number of​ customers, Hank decides to revise his compensation policies in order to provide faster and better service. He feels that a​ commission-based system, as opposed to the current​ straight-time pay​ system, will incentivize his workers to service more cars in lesser time. His​ partner, Larry​ Gomez, does not agree. He argues that the commission system will not significantly increase the number of cars being serviced per hour. In​ fact, he feels that productivity and service quality might actually fall.   

Suppose the​ commission-based system is implemented. Which of the​ following, if​ true, would be most helpful in determining the accuracy of​ Hank’s claim?

a.the recent changes in the price of fuel

b.the increase in total cost at Prseton Mechanics

c.the changes in waiting time of customers

d.the recent changes in minimum wage regulations

e.the number of automated car washes that Preston has