Belle Auto Detailing reported the following results for the past week: Actual number of cars detailed Actual direct labor hours used Actual total direct labor cost 170 595 $6,700 Budgeted number of cars to be detailed Standard direct labor cost per hour Standard direct labor per car 200 $7.17 1.5 What is Belle's direct labor efficiency variance? O A. $2,438 unfavorable B. $2,438 favorable C. $3,828 unfavorable D. $3,828 favorable