Which of the following BEST describes the purpose of user account control (UAC) in WindowsVista?（）

• A、UAC ensures that standard users cannot access the files and folders of administrative users.
• B、UAC allows a computer administrator to add new user accounts to the system, configure passwords and settings for existing users, or remove existing user accounts.
• C、UAC ensures that viruses and other malware cannot infect the computer, eliminating the need for third-party antivirus solutions.
• D、UAC ensures that important changes cannot be made to Windows Vista without the permission of a computer administrator.