Answer:
Because the navajo languages are only spoken but never written.
To keep language on and on you need people to speak it, and people to remember it. However, from my memory, the number of navajo tribes arent much and the language is pretty hard to learn since it is only a spokent language, so there are no written records for it.
I believe the answer is sibilance correct me if i'm wrong.
B. You can be used as both. Here is an example. "You said you wanted this bear, so I got it for you." You is used as both a subject and object pronoun.
