According to the passage, it can be inferred that Elizabeth Cady Stanton's personal qualities significantly impacted the women's suffrage movement primarily through her ability to write and speak. The passage states that Stanton was "a master of words" and was able to "write and speak to perfection" about the ideas and feelings that Susan B. Anthony could not express herself. This highlights that her verbal brilliance and communication skills helped convey the movement's message effectively to the public. Therefore, the best answer is:
Her ability to write and speak helped get the movement's message heard by the public.