What was the most significant reform made during each 3 progressive presidents admistration?

Answer 1

By "progressive presidents" I assume you mean Theodore Roosevelt (1901-09), William Howard Taft (1909-13), and Woodrow Wilson (1913-21).

I don't know much about the second two, but Roosevelt passed the Meat Inspection Act (1906) as a response to growing awareness of the terrible conditions of meat packing industries (dead rats, feces, and other debris were being packaged and sold as chicken in disease-infested factories, for example), raised mainly by Upton Sinclair's book The Jungle. Europe, a major importer of American meat, was threatening to ban it altogether if conditions did not improve.

He made progress in holding rich trusts back from taking too much advantage of factory workers (trusts are business heads that control a market, almost to the extreme of a monopoly), but did not completely drain them of their wealth (Taft did twice as much trust-busting but I don't know those specifics).

Roosevelt was a conservationist, concerned with the rapid decay of America's rich resources, so he set aside lots of unclaimed forest in the west as public park land, and he allowed people to settle arid desert land as long as it was irrigated within three years, which.

However, Roosevelt was racist and sexist so he did little to directly aid equal rights reformers.