The correct answer to this open question is the following.
Prehistoric sites have geographic ‘place’ because archeologist, anthropologists, historians, and other scholars have studied the places and text that refers to ancient civilizations, and that is why we can know and identify the location of determined civilization.
For instance, the Sumerians clay tablets that were written in the cuneiform language, clearly establish the story of the Sumerians, their city-states, their gods, and part of their life. That is how archeologists and historians have proved that they existed, they settled in the middle of the Tigris and Euphrates River in modern-day Iraq, in the Middle East. Due to this information, historians know that they formed great city-states such as Kish, Nippur, Eridu, or Lagash, and the archeological ruins and texts show that they built impressive buildings called Ziguratts.
The same happens with other civilizations such as ancient Greek, China, Rome, and Mesoamerican civilizations.
Mass Society Theory.
A mass society is a society in which traditional social ties have been diminished due to prosperity and bureaucracy. According to the Mass Society Theory, the increase in size and modernity weakens the social fabric and individuals become more individualistic and socially isolated.
"Planting trees throughout Sahel" is the one action among the following actions given in the question that would be the most effective long-term solution to fighting desertification in the Sahel.
