What is the difference between a refugee and an internally displaced person?

Refugees are migrants who must have crossed an international frontier because of a well-founded fear of persecution. IDPs are people who have involuntarily been uprooted and displaced but still remain in their own countries. persons (also known as "IDPs") are "persons or groups of persons who have been forced or obliged to flee or to leave their homes or places of habitual residence

the answer is b.

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