The computation of a firm's inventory position is found by taking the inventory on hand and adding it to the on-order inventory, and then subtracting back-ordered inventory.

A) Fixed-order quantity inventory models are "time triggered."
B) Fixed-time period inventory models generate order quantities that vary from time period to time period, depending on the usage rate.
C) Safety stock can be computed when using the fixed-order quantity inventory model by multiplying a "z" value representing the number of standard deviations to achieve a service level or probability by the standard deviation of periodic demand.
D) Safety stock is necessary in any fixed-time period system.