痊愈、显效、进步、无效属（）

A.数值变量

B.独立的两类

C.不相容的多类

D.类问有程度差别

E.以上均不是

An argument against using the price-to-sales (P/S) valuation approach is that:（）

A. sales figures are not as easy to manipulate or distort as earnings per share (EPS) and book value. 

B. P/S ratios do not express differences in cost structures across companies.

C. P/S ratios are not as volatile as price-to-earnings (P/E) multiples.