Eberley Corporation's cost formula for its manufacturing overhead is $25,700 per month plus $10 per machine-hour. For the month of July, the company planned for activity of 5,900 machine-hours, but the actual level of activity was 5,920 machine-hours. The actual manufacturing overhead for the month was $86,800. The activity variance for manufacturing overhead in July would be closest to:

a. 2,100 U

b. 200 U

c. 200 F

d. 2,100 F