Which of the Following Statements Regarding Aggregate Planning Is True

Which of the following statements regarding aggregate planning is true?

A) In a pure level strategy, production rates or work force levels are adjusted to match demand requirements over the planning horizon.
B) A pure level strategy allows lower inventories when compared to pure chase and hybrid strategies.
C) In a mixed strategy, there are changes in both inventory and in work force and production rate over the planning horizon.
D) Because service firms have no inventory, the pure chase strategy does not apply.
E) All of the above are true.