This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of Gastrointestinal System Including Diarrhea, Subject name: Pediatrics
[{'content': "The IgA anti TTG (Tissue Transglutaminase) is a sensitive marker for diagnosis of: \nSelect and explain. \nA. Celiac Disease, B. Eosinophilic Gastroenteritis, C. Primary Immunodeficiency, D. Crohn's Disease", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Celiac disease: specific antibodies comprise- IgA anti TTG Endomysial antibodies Antibodies against deamidated forms of gliadin peptides', 'role': 'assistant'}]