Which definition best describes the implementation service component within the implement phase？ Select exactly 1 answer（s） from the following：（）。

• A、providing a step-by-step plan that details the installation and service-commission tasks required in order to create a controlled-implementation environment that emulates a customer network
• B、assessing the ability of site facilities to accommodate proposed infrastructure changes
• C、developing and executing proof-of-concept tests， validating high-level infrastructure design， and identifying any design enhancements
• D、installing， configuring， and integrating systems components based on an implementation plan developed in earlier phases
• E、improving a customer’s infrastructure security system