Which definition best describes the staff training service component within the wireless implement phase？（）

A. develops a training plan and delivers via a custom workshop or e-learning
B. helps improve the performance and functionality of the infrastructure operations and network management system
C. reduces the risk of downtime caused by facilities-related problems
D. provides a step-by-step plan detailing the installation and service-commission requirement tasks to be staged in a controlled implementation environment that emulates a customer network