Answer:
reading background information
Step-by-step explanation:
Reading background information is the only option, among the options given, that can help identify keywords related to a specific author. This is because the reading will provide ideas, affirmations and references that will lead the reader to identify the author of a certain work. "Writing the paper", "crystallizing the idea" and "brainstorming" will not help to compensate an author because these options have other purposes.