Which of the following was not a way in which the incas adapted to their environment?

terraced hillsides to control erosion

built earthquake-resistant structures

built irrigation systems

built a system of roads

Building an earthquake-resistant structure was not the way Inca adapted to their environment.  The Inca Empire people were not able to acquire knowledge in terms of using animals to ride, they also don’t have the knowledge of iron and steel, which is greatly needed in making an infrastructure which is earthquake proof.

a stronger government

the answer would more than likely a.)falling crop prices  

hope the answer is right and ,either way have a nice day.