Incidence is determined by:

Correct option is A

Sol. Incidence refers to the number of new cases of a disease in a population during a specific time period. A prospective study is used to track new occurrences of a disease over time.
Explanation of each option:
· (a) Prospective study – Correct answer. A prospective study follows individuals over time to observe new cases of a disease, making it ideal for determining incidence.
· (b) Case Control study – This type of study compares individuals with a disease to those without it, and is better suited for studying the causes rather than incidence.
· (c) Cross sectional study – A cross-sectional study examines data at a single point in time and is used more for prevalence studies, not incidence.
· (d) Retrospective study – A retrospective study looks at past data and is more useful for understanding the causes of diseases rather than calculating incidence.