This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Parasitology Pa 1 (Protozoology), Subject name: Microbiology
[{'content': 'The normal habitat of giardia is - \nSelect and explain. \nA. Duodenum and Jejunum, B. Stomach, C. Caecum, D. Ileum', 'role': 'user'}, {'content': 'Answer: A \nExplanation: GIARDIA LAMBLIA: Habitat: Mucosa of duodenum and upper ileum of man. Morphology: 2 forms: Trophozoite and Cyst Infective stage: Cyst, Route of infection: Feco-oral route Cyst transforms to trophozoites which multiply in duodenum, attach to GIT mucosa by adhesive disk and later on, shed in the lumen, transforms to cysts which are passed in feces. They are the diagnostic form of the parasite. E.histolytica resides in distal ileum and caecum.', 'role': 'assistant'}]