Repeating an expeiment with different subject groups and conditions in experimental research is aa.Advantageb.Disadvantagec.constraintd.concern

In experimental research, repeating an experiment with different subject groups and conditions is widely recognized as an advantage. This process, often referred to as replication, enhances the reliability and validity of the findings. By employing diverse subject groups, researchers can determine whether the results are consistent across various populations or situations, thus reducing the possibility of bias that may stem from a single sample.

Moreover, testing under different conditions can help identify the range in which the effects observed hold true. It allows researchers to account for variables that may influence the outcome, leading to more generalized conclusions. While there may be practical challenges in terms of resources and time, the benefits of establishing robust and replicable results far outweigh these concerns.

Final Answer: a. Advantage