Global Engineering's Actual Operating Income for the Current Year Is

Global Engineering's actual operating income for the current year is $50,000. The flexible budget operating income for actual volume achieved is $40,000, while the static budget operating income is $53,000. What is the sales volume variance for operating income?

A) $13,000 favorable
B) $10,000 unfavorable
C) $13,000 unfavorable
D) $10,000 favorable