You need to complete the application

You are developing a SharePoint solution for a company. You create one site collection for each department.
Sites may use data from internal or external web service endpoints. You are developing an application that
allows site owners to add or change web service endpoints.
The application must run in the context of the site owner.
You need to complete the application.
What should you do?

A.
Use the SPWebConfigModification class to add a list of web service endpoint URLs to the web.config file.

B.
Add a property named WebSvcEndpoint to the SPSite.Properties property bag. Store a web service
endpoint URL as a value.

C.
Add a property named WebSvcEndpoint to the SPWeb.AllProperties property bag. Store a web service
endpoint URL as a value.

D.
Add a list of web service endpoint URLs to the SPFarm.Properties hashtable.

Explanation:
The SPWebConfigModification class holds modifications that are made to the web.config.
Each endpoint supported by your WCF service application must be defined in the web.config settings for the
application.
Using Service Endpoints
https://msdn.microsoft.com/en-us/library/office/ee535060(v=office.14).aspx