Bill Yates, CFA, is evaluating NanoSoft, Inc. , a high tech company with impressive sales growth but no earnings. Yates' supervisor, a firm believer in relative valuation, instructs him to use the price-to-sales multiple to determine the value of NanoSoft. In an e-mail to his supervisor, Yates weighs the pros and cons of the price-to-sales multiple. All of his statements about price-to-sales ratios are correct EXCEPT:（）
A. profit margin is a key variable not considered.
B. price-to-sales is a poor valuation technique for growth companies.
C. sales growth drives all subsequent earnings and cash flows.