Your company has an Exchange Server 2010 Service Pack (SP1) organization and a hybrid deployment of
Office 365. You have two federation servers named Server1 and Server2. You manage Server1 and Server2 by
using a user account that is a member of the Domain Admins group. You need to set the authentication method
of the federation servers to forms-based authentication. What should you do?

A.
Modify the Web.config file in the %systemroot%\\inetpub\\adfs\\Is directory.

B.
Modify the Global.asax file in the %systemroot%\\inetpub\\adfs\\Is directory.

C.
From the AD FS 2.0 Management console, add a claims provider trust.

D.
From the AD FS 2.0 Management console, add a relaying party trust.

Explanation:
To configure a non-default local authentication type, navigate to inetpub\\adfs\\ls located in the root folder, Select
web.config and Edit in Notepad. The use Ctrl+F to find <localAuthenticationTypes>, Cut your preferred local
authentication type (the entire line), and Paste it to the top of the list before saving and closing the web.config
file.
https://blogs.technet.microsoft.com/educloud/2012/10/03/fba-customization-with-office-365-andadfs/