A Store Has Annual Average Daily Demand Rate of 16

A store has annual average daily demand rate of 16 units with a standard deviation of 2 units,and the time between orders is 90 days and the lead time for it to receive an order from its supplier is 20 days,if the supplier visits the store and there are 6 units of inventory in stock,the store's safety stock for a 95% service level is approximately

A) 36.2
B) 43.8
C) 16.2
D) 28.6