This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'In ataxia, telengiectasia which is seen- \nSelect and explain. \nA. Ig G absent, B. Ig M absent, C. Ig A absent, D. Ig A structure abnormality', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]