So much is at stake in writing a conclusion. This is, after all, your last chance to persuade your readers to your point of view, to impress yourself upon them as a writer and thinker. And the impression you create in your conclusion will shape the impression that stays with your readers after they've finished the essay.
Abstract nouns are nouns that the five senses can not detect. Honesty is like honestly. You cannot see honesty, you can not feel honesty, you cannot see honesty, you can not taste honesty, and you can not hear honesty. So, it is an abstract noun.
I would say the correct answer is that has an undetermined answer.
If a subject has been thoroughly covered, then there is no need for this researcher to do it all over again. If it's impossible to answer, there is no need to try. If it can be answered easily, then it doesn't really require a research. This leaves us with the last option, because a researcher might want to try and determine the answer.
Answer:
Inference and ask questions.
Explanation:
I dunno what answer yu were looking for, but this seems right to me.