Danika should research the author of each piece. This step is important because understanding the author's qualifications, background, and expertise can help assess the credibility and reliability of the research source. Knowing whether the author has relevant experience or credentials in the field can provide additional context for evaluating the validity of the information presented.
The other options, while potentially useful in certain contexts, do not directly address the validity of the sources in the way that researching the author does.
As for classifying the style of writing: the suggestions primarily focus on evaluating the credibility of research sources rather than discussing writing style. The style of writing could be relevant in analyzing the effectiveness of communication, but for validity assessment, understanding the author's background takes precedence.