Midend's Camera Shop has prepared the following flexible budget for September and is in the process of interpreting the variances. F denotes a favorable variance and U denotes an unfavorable variance. Variances Material A Material B Material C Flexible Budget $29.000 37,000 44,000 Price $1,200 U 800 F 1,500 U Efficiency $1,900 F 700 U 2.500 F The explanation that lower - quality materials were purchased is most likely for O A. Material A OB. Material B OC. Material C OD. both Material A and C