Andy's Basketball Manufacturing Company reported:

Actual fixed overhead $500,000

Fixed manufacturing overhead spending variance $30,000 unfavorable

Fixed manufacturing production-volume variance $20,000 unfavorable

To isolate these variances at the end of the accounting period, Brandon would:

A) debit Fixed Manufacturing Overhead Allocated for $500,000

B) debit Fixed Manufacturing Overhead Spending Variance for $30,000

C) credit Fixed Manufacturing Production-Volume Variance for $20,000

D) credit Fixed Manufacturing Control Allocated for $450,000

I know the answe is B, but WHY?