True about carriers ?

Ans. is 'b' i.e., Serves as source of infection A carrier is defined as "an infected person or animal that harbours a specific infectious agent in the absence of clinical disease and serves as a potential source of infection". As a rule carriers are less infectious than cases, but epidemiologically they are more dangerous than cases because they escape recognition, and continuing as they do to live a normal life among the population or comunity, they readily infect the susceptible individuals over a wider area and longer period of time.