Point of view about index creation

Hello Everybody,
i have a table BusineesGeoChildren(BusinessGeoId,BusinessGeoChildId).
Primary key=(BusinessGeoId,BusinessGeoChildId).
but the main select against this table is(the most used query used for this table):SELECT BusinessGeoChildId FROM BusineesGeoChildren WHERE BusinessGeoId=BusinessGeoId0.
Is it recommended to create a nonclustred index on the column BusinessGeoId?

In SQL Server, a primary key already includes an index (in fact like all unique constraints). Since the BusinessGeoId column is the first column on the index, you do not need a separate index.

OKi.Thanks