Correct Response: A. In order for the results of scientific investigations to be valid, they must be reliable. Reliability can be enhanced by ensuring that results are similar when experiments are repeated. In scientific investigations, a control is a sample that is not manipulated by the experimental variable. A set of data (B) would not be considered a control in this situation. Repeating the experiments may help improve the precision of observed measurements, but it cannot eliminate the potential for human error (C). While repeating the experiments may provide an opportunity to practice the procedure (D), this likely would not be the primary reason for doing so.
