Final answer:
Increasing the sample size is an effective action to improve the quality of experimental design results. This provides greater reliability and accuracy in the experiment. The presence of a control group and careful control of variables also contribute to maintaining the integrity of the experiment.
Step-by-step explanation:
To improve the quality of the results when developing an experimental design, a scientist could take several actions. Among the listed options, increasing the sample size (A) is a beneficial approach. A larger sample size enhances the reliability of the results by reducing the impact of outliers and allowing for more accurate generalizations to the larger population.
Additionally, experimental designs should include a control group to serve as a baseline for comparison. This allows researchers to conclude with greater certainty that any observed effects are due to the experimental manipulation and not some other factors. Furthermore, it is important to limit and carefully control variables. Reducing the number of variables (B) is crucial to isolate the effects of the independent variable on the dependent variable and maintain the integrity of the experiment.
Skipping the control group (C) or conducting the experiment in a different season (D) could introduce confounding variables or seasonal effects, which can compromise the validity of the experiment.