Hamp Kennel uses tenant-days as its measure of activity; an animal housed in the kennel for one day is counted as one tenant-day. During December, the kennel budgeted for 3,000 tenant-days, but its actual level of activity was 3,050 tenant-days. The kennel has provided the following data concerning the formulas to be used in its budgeting: Fixed element Variable element per per month Revenue. Wages and salaries.... Expendables. Facility expenses.. Administrative expenses. Total expenses... tenant-day $31.10 $2,500 $5.90 500 11.80 9,400 2.90 7,300 0.10 $19.700 $20.70 10. The net operating income in the planning budget for December would be closest to: A. $11,500 B. $13,420 C. $12,984 D. $12,020