only stuck on part c. please provide answer and explain.

5. Develop an MRP spreadsheet record for six periods using the following parameters for the item un . Period Gross requirements 1 20 2 20 3 40 4 30 5 30 6 30 Lead time Lot size Safety stock Inventory Scheduled receipt 1 period 50 units 0 units 2 units 50 units in period 1 a. In what periods are there planned order releases? b. What happens to the timing. number of planned order releases, and average inventory (for periods through 6) if 15 units of safety stock are required? c. What happens to the timing, number of planned order releases, and average inventory (for periods through 6) if a one-week safety lead time is used instead of the safety stock? 6. Given the following product structure diam