The following standards for variable manufacturing overhead have been established for a company that makes only one product:

Standard hours per unit of output	5.6	hours
Standard variable overhead rate	$12.00	per hour

The following data pertain to operations for the last month:

Actual hours	2,550	hours
Actual total variable manufacturing overhead cost	$31,210
Actual output	200	units

What is the variable overhead efficiency variance for the month?

A. $17,770 U

B. $17,160 U

C. $610 F

D. $13,440 F