A researcher wants to test the assertion that in comparison to female politicians, male politicians in the 20th century were involved in more number of fraud cases. Which will be the most suitable observation method in this scenario?

archival research

Explanation: this is a type of research that uses existing records as data. That is preexisting database e. g birth certificates, marriage licenses. In this case, the researcher will look for the archives of male and female politicians in fraud cases.