Kaina Clinic uses client-visits as its measure of activity. During May, the clinic budgeted for 3,000 client-visits, but its actual level of activity was 2,970 client-visits. The clinic has provided the following data concerning the formulas used in its budgeting and its actual results for May: Data used in budgeting: Fixed element per month Variable element per client-visit Revenue $ 0 $ 25.80 Personnel expenses $ 20,200 $ 7.10 Medical supplies 900 4.60 Occupancy expenses 5,500 0.70 Administrative expenses 3,500 0.20 Total expenses $ 30,100 $ 12.60 Actual results for May: Revenue $ 78,246 Personnel expenses $ 42,647 Medical supplies $ 15,002 Occupancy expenses $ 7,289 Administrative expenses $ 4,294 The activity variance for personnel expenses in May would be closest to:

a. 213 f

b. 1147 u

c. 213 u

d. 1147 f