The Adage "When in Rome,do as the Romans Do" Refers

The adage "When in Rome,do as the Romans do" refers to

A) an international trader in a foreign situation should seek to behave as the Romans did.
B) an international trader in a foreign situation should seek to model his behavior on that of his hosts.
C) an international trader in a foreign situation will always "stick out" and cannot blend in.
D) an international trader in a foreign situation should seek to behave, as much as possible, as if he were home.
E) None of the above