Override the default Source Qualifier join

Under what circumstances should a user override the default Source Qualifier join?

Choose Answer

(A)
The datatypes of the columns used in the join condition do not match.
(B)
The Source Qualifier is being used to join two tables located on different database servers (a heterogeneous join).
(C)
The Source Qualifier is being used to join two or more flat files.
(D)
The order of the Source Qualifier ports has been changed since the mapping was first saved.