Which three of the following are some of the leading practices when modeling the Business model and mapping layer?

Which three of the following are some of the leading practices when modeling the Business model and mapping layer?

A.
Combine all attributes that describe a single entity

B.
Create system ODBC in this layer

C.
Delete logical columns that map to keys of physical dimension tables

D.
Delete key columns as they will not be exposed to the analytic WE UI

E.
Make the logical columns names unique within a subject area

F.
Make sure that extension tables are accessed only when necessary