The best analysis of how migration can change culture is:
Migration can spread cultural ideas to destination regions, but in recent eras it has had more of an effect on source regions.
This option acknowledges the influence of migration on both the destination and source regions, implying that cultural exchange is a two-way street. In modern contexts, migration can lead to significant changes in the cultural landscape of source regions as well, due to factors like remittances, transnational ties, and the sharing of ideas and practices between migrants and their home communities.