HIV prevalence can be assessed bv-

Ans. is 'a' i.e., Sentinel surveillance Surveillanceo Surveillance is defined as "the continous scrutiny of the factors that determine the occurrence and distribution of disease and other conditions of ill healtho S urveillance may be of following typesPassive surveillanceData is reported itself to health system, e.g. a patient (clinical case) is coming to a doctor.Most of the national health programmes in India rely on passive surveillance for data collection.Active surveillanceData is collected actively by health system, e.g. collection of blood slides every fortnight from house to house to control malaria.Active surveillance in India is done inNational leprosy elimination programme (modified leprosy elimination campaigns}.National vector Borne disease control programme (NVBDCP) e.g. malaria.Sentinel surveillanceSentinel surveillance helps in identifying missing cases and supplementing notified cases.Sentinel surveillance in India is done in national AIDS control programme.