Allen Company's master budget called for 50,000 units of production. Budgeted direct material costs at this level were $450,000 or $9 per unit. Allen actually produced 54,000 units and incurred direct material costs of $496,000. What is Allen's direct material variance using flexible budgeting?

a. $10,000 U
b. $46,000 U
c. $36,000 U
d. $10,000 F