The answer is C. It brought out the idea of women's suffrage.
Like other guy said, it is the most logical, but it is also a document specifically about the rights of women.
If you do a quick google search about the document and the author you will find a brief synopsis of the document (explaining that it is about the rights of women) and that the author was a suffragist.
Another google search about the timeline you will find that the document didn't actually bring about the idea of women's suffrage. It was actually just marking the official beginning of women's suffrage, just like the Declaration of Independence. The document was signed at the first women's rights convention in America. If you search the start of women's suffrage it will say that it started in 1848, the same year that the Declaration of Sentiments was signed (There is no exact time for it obviously, but that is the main time when it was being noticed widely).
Hopefully this helps you guys understand a little more! Typically with questions like this you can easily find the answer by doing simple google searches like this.