Los ríos han sido clave en el desarrollo de importantes culturas de la historia.

answer; the best answer is (demand);

since learning about his learning patterns, logan has become very aware of the thoughts and feelings he experiences as he listens to the “internal chatter” of his patterns.

even though you have attached neither the chart nor the generalizations, i have located them online. the right answer is d, since they are asking you about a generalization. you can only infer from the chart that between 2008 and 2009 the number of employed workers decreased significantly (from over 115 millions to 107 millions approximately), which signals some type of economic crisis.  

i believe your answer is mountains.