Incidence is calculated by -
Ans. is 'b' i.e., Cohort study CharacteristicsCohort StudyCase control StudyCross Sectional StudyDesignProspectiveRetrospectiveOne point in timeIncidenceEstimatedNot estimatedNot estimatedPrevalenceNot estimatedNot estimatedEstimatedCalculationso Incidence rateso Relative risko Attributable risko Odds ratio