Which file extension should you use for the announcement file?

Your network contains a server that runs Windows Server 2008 R2.
You install Windows Media Services on the server.

You need to create an announcement file that allows Windows Media Player clients to decode multicast streams.

Which file extension should you use for the announcement file?

A.
.asx

B.
.htm

C.
.nsc

D.
.wsx

Explanation:
Announcing content

Before you can stream content, you need to let your users know that it is available by using an announcement. An announcement is a Windows Media metafile with an .asx extension that provides the Player with the information needed to connect to a Windows Media server to receive content. You can place a link to an announcement on a Web page, make the announcement available in a shared file, or send an announcement in an e-mail message. Users can access your content either by clicking the link to the announcement on a Web page or by opening the announcement directly. The announcement wizards on the Announce tab of the Windows Media Services snap-in help you create announcement files (.asx files) and multicast information files (.nsc files) that players can use connect to your content. The wizards can also help you create a Web page with an embedded Windows Media Player control or provide you with the syntax to embed a Player in your own Web page.

Source: http://technet.microsoft.com/en-us/library/cc753414.aspx