On September 1, the production department had 18,000 units 45% complete as to labor and overhead; materials are added at the beginning of the process. During September, 90,000 units were started. At the end of September, the ending goods in process of 24,000 units were 75% complete as to labor and overhead. What was the number of units completed & transferred to the next department?

a. 100,200

b. 93,000

c. 84,000

d.79,800