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': 'Commonest side effect of antihistaminics is? \nSelect and explain. \nA. Sedation, B. Tinnitus, C. Euphoria, D. Lassitude', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Sedation o Sedation, diminished aleness, concentration, light headedness, motor in coordination, fatigue and tendency to fall asleep are the most common side effects.", 'role': 'assistant'}]