You need to ensure that users can update only the phone numbers by using this view

You have three tables that contain data for vendors, customers, and agents. You create a view that is
used to look up telephone numbers for these companies.
The view has the following definition:

You need to ensure that users can update only the phone numbers by using this view.
What should you do?

A.
Alter the view. Use the EXPAND VIEWS query hint along with each SELECT statement.

B.
Drop the view. Re-create the view by using the SCHEMABINDING clause, and then create an index
on the view.

C.
Create an AFTER UPDATE trigger on the view.

D.
Create an INSTEAD OF UPDATE trigger on the view.

Explanation:
http://msdn.microsoft.com/en-us/library/ms187956.aspx