Which one of the following statements is best?
◦ The level of safety stock maintained decreases when the standard deviation of demand during lead-time increases.
◦ The level of safety stock maintained is greater if mean absolute deviation (MAD) is used rather than standard deviation in estimating forecast errors.
◦ When no safety stock is maintained, stockouts will occur during approximately 50% of the cycles.
◦ The level of safety stock maintained decreases when the desired cycle-service level increases.