问题：

[单选] All client computers on your company network were recently migrated from Windows XP to Windows 7. Employees use Internet Explorer 8. Each time employees access a Web application, they are prompted to install an add-on. After each installation, the application restarts and prompts the employees to install the add-on again. You need to ensure that employees can run the application. What should you do?（）

A . Use a script to install the add-on in Windows XP Mode.
B . Use a script to run the application in Windows XP Compatibility Mode.
C . Add the class identifier of the add-on to the Add-on list in Group Policy.
D . Set the Deny all add-ons unless specifically allowed in the Add-on list Group Policy setting to Disabled.