What might be the cause of this?

After the migration to SAP S/4HANA 1809, you notice in the currency configuration of the company code that the global currency has the "Currency Is Only Available In Controlling" indicator.

What might be the cause of this?
A . Before the migration, the group currency of the controlling area was defined as a parallel currency in the company code.
B . Before the migration, the company code was NOT linked to a controlling area.
C . The controlling area linked to the company code was defined with currency type 20.
D . Before the migration, the company code did NOT have any parallel currencies defined.

Answer: C,D