According to the passage, it can be inferred that Elizabeth Cady Stanton's personal qualities, particularly her ability to write and speak effectively, helped get the movement's message heard by the public. This is supported by the description of her verbal brilliance and her capacity to articulate ideas that her collaborator, Susan B. Anthony, felt but could not express herself. Therefore, the most appropriate response is:
Her ability to write and speak helped get the movement's message heard by the public.