问题如下：
An industry with high barriers to entry and weak pricing power most likely has:
选项：
A. high barriers to exit.
B. stable market shares.
C. significant numbers of issued patents.
解释：
A is correct.
An industry that has high barriers to entry generally requires substantial physical capital and/or financial investment. With weak pricing power in the industry, finding a buyer for excess capacity (i.e., to exit the industry) may be difficult.
从行业利润的角度来看，最好的情况是进入壁垒较高而退出壁垒低，进入壁垒较高，新进入者将受到抵制，而当该行业不景气时，退出壁垒低不会导致过剩的生产能力仍然留在该行业内，企业不会因竞争不利而陷入困境，此种情况下企业的定价能力较高。所以这道题说进入壁垒高但是其定价权低，说明该行业的退出壁垒较高，也是说明当行业不赚钱的时候企业不能马上改行做别的。
B选项不对。稳定的市场份额说明竞争少，议价能力更高。
C选项不对。公司有大量的专利权，专利权会提高公司的定价能力
请问，答案里所说的“定价壁垒高但定价权低”是如何推出“退出壁垒高”的？
