Concept:Blood in urine after swimming in a pond suggests schistosomiasis (bilharzia).Explanation:Schistosomiasis is contracted through contact with freshwater contaminated by the larvae of the blood fluke Schistosoma haematobium.The parasite lives in the urinary bladder and blood vessels, damaging tissues and causing haematuria (blood in urine).Swimming or wading in infected ponds is a common way to contract the disease.Answer:A. schistosomiasis