Fixed costs remain constant at $400,000 per month. During high-output months variable costs are $320,000, and during low-output months variable costs are $80,000. What are the respective high and low indirect-cost rates if budgeted professional labor-hours are 16,000 for high-output months and 4,000 for low-output months? : a. $45.00 per hour; $120.00 per hour b. $25.00 per hour; $20.00 per hour c. $45.00 per hour; $45.00 per hour d. $20.00 per hour; $120.00 per hour