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