6. The following data has been collected for use in analyzing Marshall's behavior of maintenance costs Month January Machine Hours 1,600 Maintenance Costs $20,000 February March April May June July 25,000 27,200 19,600 21,400 28,400 23,600 2,100 2,600 1,700 2,400 2,500 2,300 Using the high-low method to separate the maintenance costs into their variable and fixed cost components, these components are a. $7.20 per hour plus $7,200 b. $11.00 per hour plus $8,800 c. $7.20 per hour plus $8,480 d. $11.00 per hour plus $900