The easiest way to eliminate this answer is to recognize that the author doesn’t “endorse” an alternative to the solution of teaching traditional languages. The author never suggests that there’s a better way to preserve traditional languages besides community self-teaching. Although she describes one view that community self-teaching isn’t necessary, this doesn’t constitute the author’s endorsement of that view.

The easiest way to eliminate this answer is to recognize that the author doesn’t “propose” an alternative way of implement a solution at the end. The author never expresses an opinion about how a community should try to preserve its own languages. She merely describes what some tribes are doing and some people’s viewpoint about the necessity of writing down oral languages. At no point does the author make her own proposal for what to do.

This is the best answer. P1 introduces the problem of loss of traditional languages and a solution (community self-teaching). P2 identifies a method of implementing community self-teaching (start by documenting grammar, and then arrange grammar information by complexity). P3 and P4 describe obstacles to the solution (writing down sounds, dialect issues). And P5 describes a challenge and a counter (some say we can just practice the oral language, others say oral language is in decline).

The easiest way to eliminate (D) is to recognize that the author doesn’t discuss application of a solution to “other similar problems.” The author doesn’t apply the idea of community self-teaching to anything else. She simply describes how some tribes are using this solution to preserve their traditional languages. Whether other things can be self-taught by a tribe is not discussed.

The easiest way to eliminate (E) is to recognize that the author doesn’t reject the solution of community self-teaching. We can debate whether it’s even appropriate to call community self-teaching a “proposal,” but setting that issue aside, even if we consider it a proposal, (E) is inaccurate when it states that the proposal is rejected.