Gourley Clinic uses client-visits as its measure of activity. During August, the clinic budgeted for 4,050 client-visits, but its actual level of activity was 3,970 client-visits. The clinic has provided the following data concerning the formulas to be used in its budgeting:

	Fixed element per month	Variable element per client-visit
Revenue		$40.70
Personnel expenses	$36,700	$11.90
Medical supplies	2,700	8.70
Occupancy expenses	9,700	2.70
Administrative expenses	6,700	.90
Total expenses	$55,800	$24.20

The activity variance for net operating income in August would be closest to:

$1,320 U

$1,320 F

$570 U

$570 F