Which of the following statements is true? Select one: O a. The high-low method is used to derive an estimated line of cost behavior by graphically connecting the two cost amounts identified with the highest and lowest volume levels. O b. In approximating the cost function, the account analysis classifies costs based upon an industrial engineer's evaluation of production methods, and material, labor, and overhead requirements. O c. The high-low method of deriving an estimated cost line uses all the data points available. O d. The most complex of the cost estimation methods is the high-low method. e. Engineering approach approximates cost function by classifying each account as either variable or fixed based on the analyst's knowledge of how the account behaves