Atkinson Landscaping applies variable overhead based on direct labor hours. At the beginning of the current year, Atkinson had estimated the following:

Estimated variable overhead $56,000

Estimated units of production  10,000 units

Standard direct labor hours per unti 2.5 hours

During the year, 11,000 units were produced using a total of 27,200 direct labor hours and actual overhead costs were $60,000.

Refer to the Atkinson Landscaping information above. Atkinson's variable overhead efficency variance for the year was:

a. $672 F

b. $928 F

c. $4,000 U

d. $145 U