Besides data and expert testimony, what else strengthens an argument?

• A. The author's personal opinions without evidence.
• B. The length of the article.
• C. A variety of credible supporting details, such as statistics, quotes from authorities, and case studies.
• D. The color scheme of the publication.

Answer: (C)

A strong argument relies on credible evidence from multiple sources. Besides data and expert testimony, adding a variety of credible supporting details—such as statistics, quotes from authorities, and case studies—makes the case more convincing.

Why this works: statistics provide concrete numbers you can verify and compare, quotes from authorities bring trusted expertise, and case studies show real-world examples and outcomes. Together, they build a well-rounded, trustworthy picture that helps readers see that the claim isn’t based on guesswork.

For example, if you’re arguing that later school start times help students, you could include sleep-related statistics, a pediatrician’s statement supporting later start times, and a case study from a district that shifted its start time and tracked results.

Personal opinions without evidence don’t provide proof; simply making the article longer doesn’t guarantee stronger reasoning; and the color scheme or layout of a publication doesn’t affect the argument’s validity.