问题：

[单选]

You design a Business Intelligence （BI） solution by using SQL Server 2008. 
The solution includes a SQL Server 2008 Analysis Services （SSAS） database. The database contains a cube named Financials. The cube contains objects as shown in the exhibit. （Click the Exhibit button.） 
A calculated member named Gross Margin references both Sales Details and Product Costs. You need to ensure that the solution meets the following requirements： 
Managers must be able to view only their cost centers percentage of the companys gross margin.  The impact on query performance is minimal. What should you do？（）

A .  Add dimension-level security and enable the Visual Totals option.
B .  Add cell-level security that has read permissions on the Gross Margin measure.
C .  Add cell-level security that has read contingent permissions on the Gross Margin measure.
D .  Change the permissions on the Managers dimension level from Read to Read/Write.