The correct answer is C. To contrast the different living conditions for the middle and working classes.
Step-by-step explanation
The text is about the living conditions in industrial cities, especially of the middle class and the working class. In this, the author contrasts the two social classes. While the middle class lived on the outskirts of the cities with transportation facilities such as trams to go home from work; the workers lived in the poorest parts of the cities. In addition, it highlights that living conditions in these areas worsened once the displacement to large industrial cities began, due to increased epidemics and insecurity. According to the above, it can be inferred that the correct answer is C. To contrast the different living conditions for the middle and working classes.