Which of the following statements is true? I. The equivalent units in beginning work in process inventory plus the equivalent units in ending work in process inventory equals the units transferred out plus the equivalent units for the work done during the period. II. When all materials are added at the beginning of the production process, under a weighted-average process costing system the equivalent units for materials is equal to the units completed and transferred out. III. In process costing, the equivalent units computed for materials is generally the same as that computed for conversion costs. Multiple Choice None of the statements are true. Statements I and III are true. Statements II and III are true. All of the statements are true.