Sendstars is a package delivery company that recently made a study on its customer retention and service renewal metrics. They found that most customers defected from using Sendstars' services due to customer dissatisfaction stemming from delivery personnel being rude or ill-mannered. To curb this issue, Sendstars gave special training to its employees in customer service. Which of the following data mining approaches did Sendstars employ when they decided to train their employees in customer care based on the study?A. association
B. classification
C. cause-and-effect modeling
D. reduction