Final Answer:
The answer of the given statement that "Jacob Riis, in How the Other Half Lives, and Lincoln Steffens, in The Shame of the Cities, contributed to reform movements in the United States by" is (1) exposing poverty and corruption
Step-by-step explanation:
Jacob Riis, in "How the Other Half Lives," and Lincoln Steffens, in "The Shame of the Cities," were both muckraking journalists who played significant roles in exposing and highlighting the issues of poverty and corruption in the United States during the Progressive Era.
Their investigative journalism aimed to shed light on the harsh living conditions of the urban poor and the corrupt practices within city governments.
Their works contributed to the broader reform movements of the Progressive Era by raising awareness about social issues and advocating for change.
Therefore, option (1) exposing poverty and corruption is the correct answer.