Final answer:
Progressive reformers in the early 1900s used muckraking journalism as a key tactic to inform and inflame public opinion, which is best represented by option B: using media to inflame public emotions about the issue.
Step-by-step explanation:
In the early 1900s, progressive reformers used a variety of tactics to address socioeconomic problems created by poverty. They were united by the determination to reform society and improve the lives of the working poor. An important tactic utilized by these reformers was the use of muckraking journalism to draw public attention to social ills. Muckrakers published articles and books that highlighted social inequities, such as child labor and poor working conditions, thereby informing and galvanizing the middle class to push for change. Therefore, the answer is B. using media to inflame public emotions about the issue. Furthermore, grassroots Progressives pushed for direct democracy through state-level reforms and many reform initiatives took place at the state and local levels with a focus on increasing public support to influence politicians. Other tactics also included running for office, promoting worker's rights through unionization and strikes, and pursuing federal legislation for problems like child labor.