<prompt> In case control study of buccal carcinoma:CA is commoner in zarda pan users than non-usersZarda pan is a cause of buccal CAZarda pan is associated with buccal CAIf use of zarda pan is stopped, number of cases will reduce  <response>: Ans. is c i.e. Zarda pan is associated with buccal Ca. In a case control study, case and effect relationship is not established, we only get to know about associated factors. 