Which of the Following Statements About the Key Features of Cost

Which of the following statements about the key features of cost accounting and cost management is true?

A) When making decisions about what products to produce, managers need to know how revenue and costs vary with changes in output levels.
B) Managers need to understand that period costs remain the same from one period to the next.
C) The costing system allocates direct costs and traces indirect costs to products.
D) When making decisions, managers must understand that all revenue and costs are relevant.
E) Cost accounting is used for managerial decision making, not for financial statements.