Brummer Corporation makes a product whose variable overhead standards are based on direct labor hours. the quantity standard is 0.1 hours per unit. the variable overhead rate standard is $8.00 per hour. in january the company produced 8,700 units using 810 direct labor-hours. the actual overhead rate was $7.80 per hour. The variable overhead rate variance for january is:

A) $91 U

B) $91 F

C) $162 U

D) $162 F