Which of the following statements about ratio analysis is correct? Select one: a. Classifying a large, well-diversified firm into a single industry often is difficult because many of the firm's divisions are involved with different products from different industries. b. General conclusions about a firm should not be made by examining one or a few ratios--ratio analysis should be comprehensive. c. Computing the values of the ratios is fairly simple; the toughest and most important part of ratio analysis is interpretation of the values derived from the computations. d. Each of the other answer choices is correct.