The power of political machines declined during which period?
a. glided age
b. reconstruction
c. progressive era
d. industrial revolution

c. progressive era

Explanation:

The progressive era is a period of time in the history of the United States in which activists and society tried strongly to make polititians and people in power accountable for what was happening in the country, while educating and helping the society into politics and taking power from the political machines, which are basically business, bosses and people in power that were able to "force" or "strongly advice" their subordinates into voting for their candidate, but through lots of work and education activists were able to inform people and helped diminish the power of the political machines.

i would say your answer is a)

sorry if im wrong