Which limitation refers to having an inadequate number of subjects in a study?

The correct answer identifies a limitation in research studies where having an inadequate number of subjects hinders the reliability and validity of the results. When the sample size is too small, it can result in insufficient data to accurately represent the population being studied. This small sample may lead to increased variability in the results and make it difficult to draw meaningful conclusions. It's especially critical in biological studies, where various factors can influence outcomes, making a broader representation essential for robust findings.

With a larger sample size, researchers can achieve greater statistical power, which enhances the ability to detect true effects or differences if they exist. A small sample might overlook these nuances, contributing to misleading results that could falsely suggest a lack of relationship or effect within the population. Thus, recognizing the importance of adequate sample size is crucial for the integrity and applicability of research findings.