Why did the National American Woman Suffrage Association hold conventions where they did?

The National American Woman Suffrage Association (NAWSA) was an organization formed on February 18, 1890, to advocate in favor of women's suffrage in the United States. ... It played a pivotal role in the passing of the Nineteenth Amendment to the United States Constitution, which in 1920 guaranteed women's right to vote.

i think the answer is d. good luck.