Think of a research topic in developmental psychology that deals with aging or changes over time. Briefly describe the different developmental designs, and select one that you would use to explore this topic. Provide a rationale as to why you would use the approach that you selected and why you believe this method is preferable to the other two in this case. Describe some of the pragmatic issues that researchers face when using the developmental designs and how these issues can threaten the validity of your results. Finally, take some time to discuss the problem of generational cohorts and whether or not you feel this would be an issue in your hypothetical study.