The Chilton Corporation specializes in manufacturing one type of desk lamp. Chilton allocates variable manufacturing overhead costs on the basis of machine hours. Chilton budgeted 0.3 machine hours per lamp and allocates variable overhead at a rate of $1.50 per machine hour. Last year Chilton manufactured 21,000 lamps, used 126,000 machine hours and incurred actual variable overhead costs of $138,600. What was Chilton's variable manufacturing overhead rate variance last year? A. $50,400 unfavorable B. $179,550 favorable C. $50,400 favorable D. $179,550 unfavorable