Final answer:
Observational studies involve observing and recording variables as they naturally occur. The economic output of a country is a variable that can be examined through observational studies.
Step-by-step explanation:
Observational studies are research methods that involve observing and recording variables as they naturally occur, without any intervention or control. Based on this definition, the variable that would most likely be examined through observational studies is option B) the economic output of a country. This is because economic output is a real-world phenomenon that can be observed and measured without any experimental manipulation. While variables such as the speed at which a test object is released and the amount of current through an electric device can be directly manipulated and measured in controlled experiments, economic output is a complex aggregate that is influenced by numerous factors and is thus better suited for observational methods.