单项选择题
Which of the following statements is TRUE about the five forces identified by Michael Porter that determine the intrinsic long-run attractiveness of a market or market segment?
A．A segment is unattractive if the company's suppliers are unable to raise prices or reduce quantity supplied.
B．A segment is attractive if it already contains numerous, strong, or aggressive competitors.
C．A segment is unattractive if buyers possess strong or growing bargaining power.
D．A segment is attractive when there are actual or potential substitutes for the product.
