Ans. is 'd' i.e., Salmonella typhimurium . Food poisoning 16-18 hrs after eating ice cream suggests S.typhimurium food poisoning. . Lets see each option - Staph aureus food poisoning has incubation period less than 6 hours. - Clostridium perfringens food poisoning has incubation period less than 16 hours. - Now two options are left - Cl. botulinum and salmonella typhimurium both can have incubation period > 16 hours. - Food sources responsible for botulism are home preserved foods such as home-canned vegetables, smoked or pickled fish, home-made cheese and similar home made food. - Salmonella typhimurium food poisoning occurs after eating contaminated meat, milk and milk products (ice cream), sausages, custards, eggs and egg products.