Final answer:
The event labeled "1" in the table is a response to industrialization and urbanization, leading to social and political reforms during the Progressive Era.
Step-by-step explanation:
The event labeled "1" in the table is a) The event was a response to industrialization and urbanization, leading to social and political reforms. The Progressive Era was characterized by a push for social and political reforms in response to issues caused by industrialization and urbanization. This event represents the efforts of reformers to address the challenges of the late 19th century such as poor working conditions, political corruption, and social inequality.