In Chapter 13 of "The Story of My Life," Helen Keller interprets the fact that Ragnhild Kaata learned to speak with a mix of admiration and introspection. Keller is inspired by Ragnhild's achievement but also feels a sense of limitation in her own situation. She recognizes that they have different circumstances—that Ragnhild had a better opportunity, possibly with better teaching or support. Ultimately, Keller expresses a realization that her own path toward communication might differ and that she may not be able to accomplish the same thing as Ragnhild.
So, the most accurate interpretation from your options is: Helen Keller realizes that Ragnhild Kaata has a better teacher than she does.