The standard costs and actual costs for factory overhead for the manufacture of 2,500 units of actual production are as follows:

Standard Costs
Fixed overhead (based on 10,000 hours)	3 hours per unit @ $0.71 per hour
Variable overhead	3 hours per unit @ $1.94 per hour
Actual Costs
Total variable cost, $17,800
Total fixed cost, $8,000

The amount of the variable factory overhead controllable variance is

a. $0

b. $2,600 favorable

c. $3,250 unfavorable

d. $3,250 favorable