To what extent did the Populists effectively challenge the established national parties in the late 19th century?

The platform also called for a graduated income tax, direct election of Senators, a shorter workweek, restrictions on immigration to the United States, and public ownership of railroads and communication lines. The Populists appealed most strongly to voters in the South, the Great Plains, and the Rocky Mountains.

Explanation:

bipartisan basally means two groups of people who dont agree with each other (republican and democrat) make an agreement or work with each other

i think the answer is d. good luck.