The growth of the Populist Party in the late 19th century was primarily a response to economic changes and social injustices that affected farmers and the working class. Among the options you provided, B) Government corruption is the most significant factor that contributed to the rise of the Populist Party.
The party emerged from a widespread frustration with the perceived corruption and inefficiency of the government, which seemed to favor big business interests over the needs of ordinary citizens, particularly farmers and laborers. The Populists advocated for reforms aimed at reducing the influence of corporations and increasing democratic control, such as direct election of senators, government ownership of railroads, and measures to curb monopolistic practices.
While low transportation rates (A) and good market prices (C) were concerns for farmers and played roles in their economic struggles, it was the broader issue of corruption and the lack of representation in government that significantly fueled the growth of the Populist movement.