Explanation
- A
Food-borne infection
(a) Food-borne infection. Infection means live microbes multiply in the gut. Botulism is not typically an infection of that kind; the pre-formed toxin does the harm.
- B
Food-borne intoxication
(b) Food-borne intoxication. Clostridium botulinum in poorly preserved food releases botulinum toxin. Illness follows ingestion of that toxin, so it is a food-borne intoxication, not an infection and not a water-borne disease. That is the official key.
- C
Water-borne infection
(c) Water-borne infection. Classic water-borne infections are cholera or typhoid, not botulism.
- D
Water-borne intoxication
(d) Water-borne intoxication. Botulinum toxin is not a water-supply poison in the exam sense; the vehicle is food, usually canned or fermented.
Summary. Official key is (b) Food-borne intoxication. Botulism is poisoning by a pre-formed bacterial toxin in food. It is not a water-borne illness and not an infection in the usual enteric sense. Infant botulism is a special gut-colonisation story, but the Prelims pairing remains food intoxication. Neighbouring names: staphylococcal food poisoning is also intoxication; salmonellosis is infection.