<prompt> The Framingham hea study is an example of-Case-control studyCoho studyRandomized controlled trialCross-sectional study  <response>: Coho study is also known as incidence study. The cohos are identified prior to the appearance of disease under investigation. The study group so defined are observed over a period of time to determine the frequency of disease among them. Ref: 25th edition, Parks Textbook of Preventive and Social Medicine, Page no. 83 