The per-unit standards for direct materials are 2 gallons at $4 per gallon. Last month, 11,200 gallons of direct materials that actually cost $42,400 were used to produce 6,000 units of product. The direct materials efficiency variance for last month was Select one: a. $3,200 favorable b. $5,700 unfavorable. c. $2,400 favorable. d. $5,600 unfavorable. e. $3,200 unfavorable