Studies in which researchers test and compare people of various ages at one point in time are known as studies.

Cross sectional studies is the correct answer.

Cross-sectional research is used to examine participants' behaviors of different ages at one point in time. These studies are useful for a variety of reasons: data collection can be proceeded rapidly, the cost is a lot lower than a logitudinal research since there is no need to keep contact and follow-up with participants as time passes, and because of that practice effects are not a problem. On the other hand, the principal limitation of this research is that the results produce information regarding age-related change, instead of development per se.

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