During August, Department Z started and completed 78,000 units and also finished 12,000 units that were 75% completed on July 31. On August 31, Department Z's ending inventory consisted of 15,000 units that were 40% completed. All manufacturing costs are incurred at a uniform rate throughout Department Z's production process. The number of equivalent full units of production for Department Z during August is:
a. 87,000.
b. 78,000.
c. 93,000.
d. 96,000.