Which of the following BEST describes how server virtualization can cut down IT costs？ （）

• A、 Server virtualization increases server application performance allowing productivity to be increased.
• B、 Server virtualization simplifies server administration and reduces the IT department staffing needs.
• C、 Server virtualization implements higher security measures at the server OS level reducing the need for other security implementations.
• D、 Server virtualization is a more efficient use of hardware for multiple servers reducing the resource utilization.