The activities of Boko Haram in Nigeria primarily demonstrate that religious radicalization can be a centrifugal force. Consequently, the correct response is:
These activities show how religious radicalization can be a centrifugal force.
Boko Haram's extremist actions have contributed to significant divisions within Nigerian society, exacerbating tensions between different religious and cultural groups, particularly between the predominantly Muslim North and the predominantly Christian South. This illustrates how cultural elements, such as religion, can create rifts within a country.