Question

lincoln steffens was considered a reformer specifically because he was a journalist. worked to expose problems in business and in politics. wrote about modern issues. was wealthy and born in the united states.

Explanation:

Lincoln Steffens was a muck - raking journalist who exposed corruption and problems in business and politics, which is what made him a reformer. Just being a journalist or writing about modern issues isn't specific enough, and his wealth and birthplace aren't related to his reformer status.

Answer:

worked to expose problems in business and in politics.