TEAS Sentence Completion Practice Test 3

This sentence has an error by using a preposition (to have migrated) in the place of an interrogative conjunction (who have migrated).
The object, which needs to be referred by the conjunction, is about people so the conjunction that is used in the appropriate option “who have migrated to more 'happening' urban issues”. Other
options use inappropriate conjunctions (where/which/whom) to the context.