The correct option would be the last one: The rise of railroads and stockyards added unpleasant smells to city centers.
One of industrialization's disadvantage is concerned with environment. It includes pollution of air, water and soil that can result in significant deterioration of quality of life and life expectancy.
Industrialization has taken on a large proportion due to trade. The fact of having consumer markets in the country and abroad associated with the development of industrial technologies has made production increase rapidly.
Of course, production needed to be stockpiled and drained. The mode of transportation was through the trains, which led to the construction of railroads to more and more near the centers, which can generate discomfort in the people.
Therefore, the fourth answer is correct (D).
The answer should be
D. The rise of railroads and stockyards