A company’s standard for a unit of its single product is $4 per unit in fixed overhead ($24,000 total/6,000 units bud¬ geted). Actual data for the period show total actual fixed overhead of $24,100 and production of 4,800 units. Its volume variance is

a. $4,800 U.

b. $4,800 F.

c. $ 100 U.

d. $ 100 F

e. $4,900 U.