ABC analysis is based upon the principle that: A. more time should be spent on class "C" items because there are many more of them. B. there are usually a few critical items, and many items that are less critical. C. an item is critical if its usage is high. D. as with grade distributions in many MBA courses, there should be more medium-level "B" items than either "A" or "C" items. E. all items in inventory must be monitored very closely