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: Pharmacology
[{'content': 'Least predictable reaction to drug: \nSelect and explain. \nA. Toxicity, B. Side effect, C. Idiosyncrasy, D. Allergy', 'role': 'user'}, {'content': "Answer: C \nExplanation: Unpredictable (Type\xa0B or Bizarre) reactions\nThese\xa0are\xa0based\xa0on\xa0peculiarities\xa0of the\xa0patient and\xa0not\xa0on\xa0drug's\xa0known\xa0actions; include allergy and idiosyncrasy.\xa0They are less common, often non-dose related, generally more serious and require withdrawal of the drug. Some of these reactions can be predicted and prevented if their genetic basis is known and suitable test to characterize the individual’s phenotype is performed.\nReference: Essentials of Medical Pharmacology Eighth Edition KD\xa0TRIPATHI\xa0page no 92", 'role': 'assistant'}]