The data below relate to the month of April for Monroe, Inc., which uses a standard cost system and a two-variance analysis of factory overhead:

Actual direct labor hours used........................................................................16,500

Standard direct labor hours allowed..............................................................16,250

Actual total factory overhead........................................................................$53,200

Budgeted fixed factory overhead.................................................................$12,000

Budgeted activity in hours...............................................................................16,000

Total overhead application rate per standard direct labor hour..................$3.25

Variable overhead application rate per standard direct labor hour............$2.50

What was Monroe's production-volume variance for April?

a.$187.50 favorable

b.$187.50 unfavorable

c.$437.50 favorable

d.$437.50 unfavorable