This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: parasitology, Subject name: Microbiology
[{'content': 'Which of the following is most severely affected in Kala azar - \nSelect and explain. \nA. Spleen, B. Liver, C. Adrenal gland, D. Bone marrow', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The parasite spread from the site of inoculation and multiplies in reticule endothelial system especially in the spleen, liver, bone marrow and lymphnodes .This leads to enlargement of these organs.It is characterized by pyrexia, splenomegaly,hepatomegaly,lymphadenopathy(Referpgn:41baveja 3 rd edition)', 'role': 'assistant'}]