Crane Manufacturing uses weighted-average process costing. All materials at Crane are added at the beginning of the production process. The equivalent units for materials at Crane would be
a. The units started plus the units in ending work in process.
b. The units started and completed plus the units in ending work in process.
c. The units started plus the units in beginning work in process.
d. The units completed and transferred out plus the units in beginning work in process.