A: OBIEE Federated Repository Instead of moving data in to a single database, OBIEE - BI Administration can access multiple databases and create a single federated repository.OBIEE BI Answer uses this federated repository and build the ad-hoc reports and dashboards.
D: Repository Metadata Consists of 3 Layers
*The Physical Layer (Schema)
*The Business Model and Mapping Layer
*The Presentation Layer
Note: star schema

Explanation
B: The problem with caching of any kind is how to deal with stale data. How you decide to deal with this depends on how time critical your business intelligence queries happen to be. OBIEE provides a wide variety of mechanisms for dealing with stale data. The cache can be purged automatically at intervals. Caching can be enabled selectively for individual physical tables, so that data in a frequently updated table is never cached.
OBIEE provides a set of ODBC procedures that can be called when ETL processes complete to programmatically purge designated tables. But, by far the best way to selectively purge the cache is to use an event polling table. This table is populated by the client database whenever changes are made to any table (by an ETL process for a data warehouse or by a table-based trigger for an OLTP database). At specified intervals the BI Server polls this event polling table and deletes from its cache any query results that are dependent on the changed data.

Explanation
Note: The Administration tool is used to manage OBIEE server and have some capabilities to automate some repetitive tasks and principally his embedded tools.
Oracle Business Intelligence Administration Tool is available only for Windows operating systems.
The Administration Tool is a Windows application that allows the BI Server administrator to create and edit repositories.
Repositories can be edited with the administration tool in either online or offline mode.
The Administration Tool also includes a session manager and a cache manager which are available in online mode. The Cache Manager displays what queries have been cached and how frequently they have been accessed. You can also select and delete items

Explanation/Reference:
Oracle BI Cluster Server Components
* Oracle Business Intelligence Cluster Controller: The Cluster Controller determines which BI Server works in the cluster. It monitors the operation of servers in the cluster. The Cluster Controller is deployed in active- passive mode.
* Clustered BI Servers: The BI Cluster Server feature supports up to 16 BI Servers in a network domain to act as a single server. BI Servers in the cluster share requests from multiple Oracle BI clients.
* Master BI Server: A clustered Oracle Business Intelligence Server is designated as the Master BI Server. The Oracle Business Intelligence Administration Tool connects to the master BI Server for online repository changes.
* Cluster Manager: The Cluster Manager is available in the Administration Tool when a repository is opened in online mode. The Cluster Manager enables Oracle BI Server clustered instances.

Explanation/Reference:
C: OBIEE Caching and Cache Seeding
Cache is a component that improves performance by transparently storing data such that future requests for the same criteria can be served much faster. Like other application cache is not virtual memory in OBIEE. In OBIEE cache will be stored as files on the Hard Disk of the OBIEE Server in the form of files. By Default caching is enabled in the OBIEE server configuration.
For time-consuming Dashboard Pages, we can use the concept of cache seeding in OBIEE, this can be configured as a scheduled job that will ensure that the data is cached and readily available as and when the user runs the dashboard.
Incorrect answers:
D: Guided navigation is a feature of Oracle BI Interactive Dashboards that enables the content and layout of Oracle BI Interactive Dashboard to change dynamically based on changes in the information being analyzed.
Specifically, sections in a dashboard page can be set up and only appear when there is "interesting" information in the data.