The total costs to process the beginning 7,000 units in progress was 21,000. 38,000 units were started and completed. There were no ending units in progress. Costs added during the period were: materials, 78,000, and labour and overhead, 36,000. The change in the per unit cost of the units started and completed and the beginning units completed is:

a. 0.5 decrease

b. 10 increase

c. 2.7 increase

d. No change