You design a SQL Server 2008 Analysis Services (SSAS) solution. Your solution has a cube. The structure of the cube is as shown in the exhibit. (Click the Exhibit button.)
Each branch does transactions by using the local currency of the country in which it is located. Daily exchange rates for all local currencies are recorded against the U.S. dollar in the FactCurrencyRate measure group.
All transactions must be reported in U.S. dollars.
You need to prepare the cube to define currency conversion.
What should you do?

A.
Create a reference relationship between FactSales and Currency.

B.
Create a reference relationship between FactCurrencyRate and Branch.

C.
Create a many-to-many relationship between FactSales and Currency.

D.
Create a many-to-many relationship between FactCurrencyRate and Branch.

Explanation:
Tip: “currency conversion” = “reference … FactSales and Currency”

http://msdn.microsoft.com/en-us/library/ms175439.aspx
All Microsoft SQL Server Analysis Services dimensions are groups of attributes based on columns from tables or views in a data source view. Dimensions exist independent of a cube, can be used in multiple cubes, can be used multiple times in a single cube, and can be linked between Analysis Services.instances. A dimension that exists independent of a cube is called a database dimension and an instance of a database dimension within a cube is called a cube dimension.
Dimension based on a Snowflake Schema Design
Frequently, a more complex structure is required because information from multiple tables is required to define the dimension. In this structure, called a snowflake schema, each dimension is based on attributes from columns in multiple tables linked to each other and ultimately to the fact table by primary key – foreign key relationships.

Snowflake Dimension
The most common variation we see in production cubes is the snowflake design. As mentioned, this is usually implemented via a dimension that links to the fact table through another dimension. To establish this type of relationship on the Dimension Usage tab of the cube designer, you simply select the Referenced relationship type. To create a referenced (or snowflake) dimension, you must model the two source tables with a common key.
(Smart Business Intelligence Solutions with Microsoft SQL Server 2008, Copyright 2009 by Kevin Goff and Lynn Langit)