问题如下图：
选项：
A. 
B. 
C. 
解释：
想请问一下，为什么评级的星不能用数字1-5用一个自变量来表示呢
NO.PZ201709270100000204 问题如下 4. Whiof the three metho suggesteSmith woulbest capture the ability of the Morningstrating system to premutufunperformance? Metho1 Metho2 Metho3 C is correct. Using mmy variables to stinguish among n categories woulbest capture the ability of the Morningstrating system to premutufunperformance. We neen – 1 mmy variables to stinguish among n categories. In this case, there are five possible ratings anwe neefour mmy variables. Aing inpennt variable thha value equto the number of stars in the rating of eafunis not appropriate because if the coefficient for this variable is positive, this methoassumes ththe extra return for a two-stfunis twithof a one-stfun the extra return for a three-stfunis three times thof a one-stfun anso forth, whiis not a reasonable assumption. 辛苦老师详细翻译一下方法一的解析，谢谢！Aing inpennt variable thha value equto the number of stars in the rating of eafunis not appropriate because if the coefficient for this variable is positive, this methoassumes ththe extra return for a two-stfunis twithof a one-stfun the extra return for a three-stfunis three times thof a one-stfun anso forth, whiis not a reasonable assumption.
这里虽然没有不懂的单词，但是放在一起确实不懂在说什么个事情。能否下引进这个1~5星的评分系统是什么成为了mmy variables的吗？谢谢
