Which of the following statements is true? 1.The materials price variance is computed based on the amount of materials purchased during the period. 2.The standard price per unit for direct materials should reflect the final, delivered cost of the materials. 3.In general, the production manager is responsible for the materials price variance. (2.5) 1) All of the statements are true. 2) None of the statements are true. 3) Both statements I and III are true. 4) Both statements I and II are true.