Dermody Snow Removal's cost formula for its vehicle operating cost is $2,930 per month plus $323 per snow-day. For the month of December, the company planned for an activity of 17 snow-days, but the actual level of activity was 16 snow-days. The actual vehicle operating cost for the month was $8,700. The spending variance for vehicle operating cost in December would be closest to:

a. $279 U

b. $279 F

c. $602 U

d. $602 F