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': 'Giardiasis is associated with which immuno disorder \nSelect and explain. \nA. Common variable immunodeficiency, B. C1 esterase deficiency, C. C8 deficiency, D. MAC deficiency', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Risk factors of Giardiasis: Gammaglobulinemia Common variable immunodeficiency Selective IgA-deficiency. Cystic fibrosis Poor hygiene Elderly debilitated persons', 'role': 'assistant'}]