Krizum Industries makes heavy construction equipment. The standard for a particular crane calls for 18 direct labor-hours at $16 per direct labor-hour. During a recent period 1,200 cranes were made. The labor rate variance was zero and the labor efficiency variance was $4,800 unfavorable. How many actual direct labor-hours were worked?

a. 21,600

b. 21,900

c. 26,400

d. 20,400