A. In several southern states, where church involvement in suffrage activities was minimal, the women's suffrage movement developed more slowly.
It gives a contrast case, suggesting that when churches weren't involved, the movement didn't grow as fast. It moderately strengthens Greene's argument through indirect correlation, but does not reinforce the mechanism of churches enabling organizing and public speaking. But C is a better option.
B. Although some early suffrage activists had backgrounds in religious reform, they deliberately established secular organizations to avoid relying on church-based institutions.
It undermines Greene's argument by showing deliberate rejection of church support.
C. Many early suffrage organizers in the Northeast were already active in church-run religious reform networks prior to their involvement in political advocacy.
It supports the mechanism of Greene's argument, that churches enabled early suffrage organizing by giving women space to act.
D. Newspaper coverage of women’s suffrage was more frequent in northeastern states than in other areas of the United States, regardless of the presence of churches.
It weakens or it's irrelevant. If church presence didn't matter to media attention, maybe churches weren't the key driver.
E. Public petitions supporting women’s voting rights in the early 1800s often used religious language, even when submitted by secular groups.
It weakens or it's neutral. Using religious language isn't the same as churches providing spaces for action.
Correct answer is C