Skelton Corporation had planned to produce 50,000 units of product during the first quarter of the current year. The company prepared the following budget on May 1:

During the first quarter, Carson produced 60,000unit and incurred total manufacturing costs of 180,000.

Refer to the information above. Which of the following amounts should not be included in Skelton's flexible budget of 60,000-unit level.

a. direct materials used, $43,200

b. direct labor, $54,000

c. Variable overhead, $27,000

d. fixed manufacturing overhead, $70,200