What is the main purpose of conducting a controlled experiment?

Conducting a controlled experiment is crucial in scientific research because it allows researchers to isolate the effect of an independent variable on a dependent variable. By carefully controlling all other variables and keeping them constant, the experiment can provide clear evidence linking changes in the independent variable to changes observed in the dependent variable. This isolation helps in identifying cause-and-effect relationships, which is fundamental to the scientific method.

Testing multiple variables at once would complicate the analysis and make it difficult to determine which variable is responsible for any observed effects. Ensuring that results are always positive is not a goal of scientific inquiry; rather, scientists strive for accurate and impartial results, irrespective of whether they confirm or refute a hypothesis. Observing natural behaviors of organisms is a different approach that may not involve manipulation and control of variables typically seen in a controlled experiment. Thus, the correct answer highlights the importance of focusing on one variable to produce reliable and interpretable results.