How were the progressive era reforms a reaction to the problems of gilded age? (political, economic, social)

The Progressive Era was a period of widespread social activism and political reform across the United States, from the 1890s to the 1920s.[1] The main objectives of the Progressive movement were eliminating problems caused by industrialization, urbanization, immigration, and corruption in government.

nuclear fission produces the atomic bomb, a weapon of mass destruction that uses power released by the splitting of atomic nuclei the fighting in iwo jima and okinawa affected the allies' pacific strategy because truman decided to drop the atomic bomb on mainland japan.

an economic reason that the south needed a reconstruction plan is that plantations, factories, and other businesses were destroyed during the war.