Answer:
A. The key words help identify your reading audience.
Step-by-step explanation:
Through the keyword, you can identify your reading audience. Like, suppose you are writing about Android developers as a keyword. Thus it clarifies that your reading audience will be Android developers mainly. However, the keyword has nothing to do with writing purposes or goals. We first analyze our goal, and then we search for the keyword that can be best for fulfilling our goals. Hence, keywords not in best identify the writing purpose or goal. Like I want to be rich by writing, Now keyword is Android developers, which is confirming that our reading audience will be Android developers mainly, but it does not confirm that we want to be rich, as we might write for charity as well. And keywords does not have anything to do with how much evidence you should cite or the appropriate length of your essay. And hence, A. is the correct option.