Which of the following is considered a primary source?

A primary source in research refers to original data or findings that have not been altered or interpreted by others, often serving as the foundation for further analysis. A randomized control trial (RCT) fits this definition as it presents firsthand results from a controlled study designed to determine the efficacy of an intervention or treatment. In this format, researchers directly gather data from participants through observation or experimentation, thereby providing new evidence about the effects of an intervention.

In contrast, systematic reviews, literature reviews, and meta-analyses compile, analyze, and synthesize existing studies or data. They summarize or interpret findings from various studies rather than presenting new experimental results, which is why they are classified as secondary sources. These types of studies rely on primary sources to draw conclusions and offer insights based on a body of existing research rather than generating original data.