A company developed the following per-unit standards for its product: 5 kilograms of direct materials at $3 per kilogram. Last month, 1,000 kilograms of direct materials were purchased for $2,900. Also, last month, 700 kilograms of direct materials were used to produce 135 units. What was the direct materials price variance for last month? a. $12,100 unfavourable b. $12,100 favourable c. $100 favourable d. $100 unfavourable