The correct answer is B. They used land bridges
Step-by-step explanation:
Most theories related to human development and expansion towards all continents claim humans first emerge in Africa and then migrate to different parts of the world including Europe, Asia, and America. Moreover, as it is estimated this occurred more than 20,000 years ago when there were no technologies such as automobiles, ships or airplanes, it is believed humans used land bridges, which are natural bridges between continents or different zones, to migrate from Africa to other continents. For example, the Bering land bridge that connected Asia and America was used for human groups to get to America. Thus, early people migrate out of Africa using land bridges.