HOTSPOT
You are developing a SQL Server Reporting Services (SSRS) solution.
You plan to create reports based on a SQL Server Analysis Services (SSAS) tabular
database configured in DirectQuery mode.
You need to configure a shared data source.
Which data source type should you use?
To answer, select the appropriate type from the drop-down list in the answer area.
Answer: 
OLEDB
“Microsoft SQL Server Analysis Services” isn’t more correct instead “Microsoft SQL Server” ?
I think so
Agree
https://msdn.microsoft.com/en-IN/library/hh230894.aspx
tested, both “Microsoft SQL Server Analysis Services” and OLEDB can work. “Microsoft SQL Server Analysis Services” should be the first choice, i think.
OLE DB providers can sometimes offer faster performance for large scale data. When choosing between different providers for the same data source, you should try the OLE DB provider first.
https://msdn.microsoft.com/en-us/library/gg492165(v=sql.110).aspx#bkmk_tips
https://msdn.microsoft.com/en-us/library/hh230898.aspx