What makes a spot like Death Valley or Moab or Organ Pipe Monument so all-fired dry? Or for that matter a huge region like the Sahara? Or the Taklimakan Desert of western China? Is it purely fortuitous that one geographical area-say the Amazon Basin-should receive buckets of moisture while another area not far away-the Atacama-Peruvian Desert-gets so precious little? The answer to that is no. Not at all fortuitous. Three different geophysical factors combine, generally at least two in each case, to produce the world?s various zones of drastic and permanent drought: (1) high pressure systems of air in the horse latitudes, (2) shadowing mountains, and (3) cool ocean currents.
Which of the following best states the question posed by the paragraph?