<prompt> Cohort study is which type of study -Descriptive observationalAnalytic observationalExperimentalControlled trial  <response>: Ans. is b i.e., Analytic observational StudyUnit of study1.Observational studies A Descriptive studies formation of hypothesis i Case reportsii Case series B Analytic studies testing of hypothesis i Case - control or case - referenceii Cohort or follow-upiii Ecological or correlational studyiv Cross-sectional or pravalence studyIndividualsIndividualsPopulationIndividuals2.Experimental intervention studies testing of hvpothesis i Randamized controlled clinical trialsii Field trials or community intervention studiesiii Community trialsiv Animal studiesPatientsHealthy peopleCommunities 