This refers to the systematic observation of a particular phenomena in order to understand the reason for occurence, the frequency of occurrence and other important questions, using the scientific method.
With this in mind, we can see that because Dr Gutierrez is making a research question examination, then his student tells him that the data cannot be disproven no matter the evidence gathered and this showed that the research study lacks falsifiability.
Answer: Afghanistan, Andorra, Estonia, Iceland, Ireland, Latvia, Liechtenstein, Lithuania, Portugal, Spain, San Marino, Sweden, Switzerland, Tibet, Vatican City, and Yemen were all neutral during the war.
