Which of the following statements best describes how urban commuting changed in the late 1800s?
subways and automobiles replaced horse-drawn trolleys.
horse-drawn trolleys replaced elevated trains and subways.
elevated trains and subways replaced horse-drawn trolleys.
automobiles replaced horse-drawn trolleys.

they sometimes resort to unethical tactics.

the great wall of china worked as a defense for the feudal states of the zhou dynasty to the north. during the warring states period more walls were put up to defend the borders of the different kingdoms. it was semi successful because despite the wall, the mongols eventually conquered china also the great wall provided protection to the economic development and cultural progress, safeguarded the trading routes such as the silk road, and secured transmission of information and transportation. @jayxboof