Your network contains an Active Directory forest.
All users have a value set for the Department attribute.
From Active Directory Users and computers, you search a domain for all users who have a
Department attribute value of Marketing.
The search returns 50 users.
From Active Directory Users and Computers, you search the entire directory for all users
who have a Department attribute value of Marketing.
The search does not return any users.
You need to ensure that a search of the entire directory for users in the marketing
department returns all of the users who have the Marketing Department attribute.
What should you do?

A.
Install the Windows Search Service role service on a global catalog server.

B.
From the Active Directory Schema snap-in, modify the properties of the Department
attribute.

C.
Install the Indexing Service role service on a global catalog server.

D.
From the Active Directory Schema snap-in, modify the properties of the user class.

Explanation:
http://technet.microsoft.com/en-us/library/how-global-catalog-servers-work.aspx
Global Catalog Partial Attribute Set
The attributes that are replicated to the global catalog by default include a base set that have
been defined by Microsoft as the attributes that are most likely to be used in searches.
Administrators can use the Microsoft Management Console (MMC) Active Directory Schema
snap-in to specify additional attributes to meet the needs of their installation. In the Active
Directory Schema snap-in, you can select the Replicate this attribute to the global catalog
check box to designate an attributeSchema object as a member of the PAS, which sets the
value of the isMemberOfPartialAttributeSet attribute to TRUE.