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

Standard hours per unit of output	5.4	hours
Standard variable overhead rate	$11.80	per hour

The following data pertain to operations for the last month:

Actual hours	2,525	hours
Actual total variable manufacturing overhead cost	$30,395
Actual output	250	units

What is the variable overhead efficiency variance for the month?

a) $15,930 F

b) $13,865 U

c) $14,465 U

d) $600 F