The standard factory overhead rate is $10 per direct labor

The standard factory overhead rate is $10 per direct labor hour ($8 for variable factory overhead and $2 for fixed factory overhead) based on 100% capacity of 30,000 direct labor hours. The standard cost and the actual cost of factory overhead for the production of 5,000 units during May were as follows:

The standard factory overhead rate is $10 per direct labor

What is the amount of the variable factory overhead controllable variance?
a. $10,000 favorable
b. $2,500 unfavorable
c. $10,000 unfavorable
d. $2,500favorable