Mike's Service Station performs oil changes for cars. Each oil change has a standard time of 0.7 direct labor hours. The standard direct labor hour rate is $15.00 per hour. Data relating to oil changes for the month of September follow: Actual number of oil changes performed 2.300 Actual direct labor hours worked 400 Actual total direct labor cost $3,600 What is the labor rate variance for September? O A. $20,700 unfavorable O B. $20,700 favorable O C. $3,600 unfavorable OD. $3,600 favorable