The correct answer is; based on birth. In ancient times, the emphasis was given on blood line. if the person was born in a wealthy household, he/she would ultimately be subjected to a lot of power.
Explanation:
In ancient times, people hardly ever cared if a person was smart or physically was strong. No matter what capabilities you had people would subject you down to your cast.
The bloodline which you carry meant that you were special or had something to offer which others didn't.
The main reason why there was a massive immigration towards the Sun Belt was because it was unoccupied relatively to the other areas of the US, this meant that new servrices and industries could be developed for the young and flourishing naiton.