A Create an ASPX file and use the @ Register directive at the top of the page to
indicate that the markup in the file is a user control. 
B Create a code-behind file for your user control that contains a class that inherits
from System.Web.UI.UserControl. 
C Create a code-behind file for your user control that contains a class that inherits
from System.Web.UI.Page. 
D Create an ASCX file and use the @ Control directive at the top of the page to
indicate that the markup in the file is a user control.