B.
How could you find something if you don't know what you're looking for?
Think about, maybe it is (D) They focused only on solving the problems & issues that had troubled their cities in the past. you see they would be focusing their city a lot because they don't what can destroy their and what can't. they have to make sure that their is no bad guys attacking their fort and that there is no problems with the way the cities were built.
hope i helped
