The actual direct labor wage rate is $8.50 and 4,500 direct labor-hours were actually worked during the month. The standard direct labor wage are is $8.00 and the standard quantity of hours allowed for the actual level of output was 5,000 direct labor hours. What is the direct labor efficiency variance?
a. $4000 favorable
b. $4000 unfavorable
c. $ 4,500 unfavorable
d. $4,500 favorable