You are designing an ASP NET Web application that allows users to specify a file to be uploaded by entering the URL of the file.
Only files that contain information in a specific internal metadata field are allowed.
You need to design a solution to reject URLs of disallowed files.
Which two approaches could you recommend?
(Each correct answer presents a complete solution Choose two )

A.
Use an OnClick method.

B.
Use an OnSubmit Java Script handler.

C.
Use a Regular Expression Validator control.

D.
Use a custom validator control.