Then, the 20 stocks with the lowest estimated return are identified forreplacement.这里是剔除波动较大的数据吗

NO.PZ201512020300000501 问题如下 1 The machine learning techniques appropriate for executing Step 1 are most likely to baseon: A.regression B.classification C.clustering A is correct. The target variable (quarterly return) is continuous, henthis calls for a supervisemachine learning baseregression mol.B is incorrect, sinclassification uses categoricor orntarget variables, while in Step 1 the target variable (quarterly return) is continuous.C is incorrect, sinclustering involves unsupervisemachine learning so es not have a target variable. 请问老师classification适用于离散变量，在基础课件的哪里呢？我没找到，辛苦老师帮忙看看，方便我们日后复习

classification clustering A is correct. The target variable (quarterly return) is continuous, henthis calls for a supervisemachine learning baseregression mol. B is incorrect, sinclassification uses categoricor orntarget variables, while in Step 1 the target variable (quarterly return) is continuous. C is incorrect, sinclustering involves unsupervisemachine learning so es not have a target variable. 请问机器学习里为何会有回归分析这种方法呢？