Final answer:
The best research question to be studied using an observational design is "How do children interact on the playground during recess?" as it involves watching and recording natural behaviors without intervention.
Step-by-step explanation:
Among the choices provided, the research question best studied using an observational design is B) "How do children interact on the playground during recess?" This question is most suitable for an observational study as it involves directly watching and recording behaviors of children in their natural environment without any intervention by the researcher. Observational studies are key in cases where manipulation of variables is not possible or ethical, such as observing behaviors or collecting data through surveys without influencing the subjects.
There are several reasons for conducting an observational study: to observe natural behaviors, when ethical considerations prevent experimental manipulation, and when a snapshot in time of a phenomenon is needed. Models are commonly used in human biology research to simulate and understand complex biological systems.
In contrast to observational studies, controlled experiments like randomized clinical trials involve direct manipulation of an independent variable to observe the effect on a dependent variable, as with the aspirin study example. However, observational studies provide valuable insight into real-world situations and can highlight correlations, though they cannot determine causation.