Sally Sue Industries produces a product whose standard selling price is $300 per unit. Demand, though not necessarily reflected in the quarterly output figures, for this product is known to be growing. Employees work 500 hours per quarter and are compensated $17 per hour. Overhead is estimated to be 1.5 times the labor cost. The multi-factor productivity ratio (based on labor, materials, and overhead) and other relevant information are included below: Units Produced Materials Cost Employees MFP 1st Quarter 2,000 $20,000 4 5.71 2nd Quarter 2,010 $23,000 4 5.58 3rd Quarter 2,560 $35,000 5 5.44 4th Quarter 2,570 $42,000 5 5.20 There appears to be a downward trend in the MFP over the course of the last four quarters. Given the above information, what would most likely reveal the area causing the change in MFP? Materials Productivity Labor Productivity Labor+ Materials Productivity Total Productivity None of the above