What is the purpose of records with primary key values of ?1? ?2? and ?3? contained in an Optim lookup table?

A.
They are seed records for every lookup table.

B.
They contain values that can only be accessed from an Optim exit/proc.

C.
They are placeholders that allow the client to quickly locate and create additional lookup tables values.

D.
They provide lookup values in cases where a lookup column contains nulls, or spaces, or zero length values.