Nonclustered index Seek Question about Index usage:

If I create a nonclustered index like 

IX_LastName_Age


Where it is created by LastName ASC and Age ASC, and there is clustered index on ID field.

Now if I run a query 

Select Age from dbo.user where Age &gt; 10


Would the execution plan use "IX_LastName_Age" or will it scan from Clustered Index?
If the table has more columns than the 3 described, it would be more efficient to scan the IX_LastName_Age index.  If the table is just those 3 columns, it may scan either the clustered index, or the IX_LastName_Age index, each would essentially be equivalent.  In no case could there be a seek given the info in this scenario.