The tell tale heart which details in the text suggest that the narrator of this story is not reliable

The fact that he believes he is sain when he truly is not.

Hope this helps. I am an expert by the way.

Not understanding this question

Question is ambiguous. depends on what your teacher defines as important and as a developed and mature writer, there is no key to an effective argument. this is why we learn the rules so that we can break them in order to make our own effective arguments.maybe try ethos, pathos, and logos. : )