In an argumentative paragraph, which type of evidence would strengthen a causal claim most effectively?

• A. Anecdotal evidence from a single case.
• B. Experimental data showing cause-and-effect relationships.
• C. Observational data without a controlled experiment.
• D. Expert opinion without data.

Answer: (B)

The main idea here is how to back up a causal claim with solid evidence. In an argumentative paragraph, showing that one thing actually causes another requires evidence that rules out alternative explanations and demonstrates that the cause leads to a change in the effect. Experimental data does this best because it actively manipulates the suspected cause and observes the result while keeping other factors constant. This setup helps establish temporal order (the cause precedes the effect) and reduces the influence of confounding variables, making it more likely that any observed change in the outcome is due to the manipulation itself. That stronger internal validity is what makes experimental data a powerful basis for a causal argument.

Anecdotal evidence relies on a single instance and lacks broad support and control, so it can’t reliably show causation. Observational data without a controlled design can reveal associations but cannot separate the effect of the cause from other lurking factors. Expert opinion without data may be insightful but isn’t enough to demonstrate a causal link without empirical support. When you want to persuade someone that X causes Y, experimental data provides the clearest, most defensible foundation.