Herston Company uses the FIFO method in its process costing system. The beginning work in process inventory in a particular department consisted of 3,600 units, two-thirds complete with respect to conversion costs. During the month, 42,000 units were started and 40,000 units were completed and transferred out of the department. The company had 40,000 equivalent units for conversion costs. The ending work in process inventory in the department consisted of: (Do not round intermediate calculations.)

a. 2,400 units, 100% complete with respect to conversion costs

b. 5,600 units, 21% complete with respect to conversion costs

c. 0 units

d. 5,600 units, 43% complete with respect to conversion costs