This one is the cause:
<span>growth of the factory system.
</span>
<span>Growth of the factory system lead to pollution (from the factory chimneys), it made people move from farms to the cities and as a result the number and size of cities increased. </span>
Would have to go with answer choice C
"<span>a. James Madison used the idea of a three branch system described in Montesquieu's "The spirit of the laws" would be the best option, since it was Madison who advocated heavily for the separation of powers. </span>