Please explain the solution to this general accounting problem with accurate principles.

Direct materials: 3.0 kilos at $8.50 per kilo Direct labor: 1.2 hours at $18.00 per hour Variable overhead: 1.2 hours at $5.00 per hour The company produced 5,200 units in May using 16,330 kilos of direct material and 6,500 direct labor hours. During the month, the company purchased 16,900 kilos of direct material at $8.75 per kilo. The actual direct labor rate was $18.50 per hour and the actual variable overhead rate was $4.80 per hour. The company applies variable overhead on the basis of direct labor hours. The direct materials purchases variance is computed when the materials are purchased. The materials quantity variance for May is: a. $7,650 U b. $7,650 F c. 6,630 U d. 38,075 F