Which of the following statements regarding process costing are true? I. When computing the cost per equivalent unit of production, it is necessary to consider the percentage of completion of the units in beginning inventory. II. When computing the cost per equivalent unit of production, prior period costs are combined with current period costs. III. When all materials are added at the beginning of the production process, the equivalent units of production for materials is equal to the units completed and transferred out. Statements I and II are true. Only Statement II is true. Only Statement III is true. Statements II and III are true