Mondo Snow Removal's cost formula for its vehicle operating cost is $1,130 per month plus $483 per snow-day. For the month of January, the company planned for activity of 21 snow-days, but the actual level of activity was 25 snow-days. The actual vehicle operating cost for the month was $12,760. The activity variance for vehicle operating cost in January would be closest to:

a. $1,487U

b. $1,487F

c. $1,932U

d. $1,932F