This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: vitamins, Subject name: Biochemistry
[{'content': 'Transketolase activity is seen with which vitamin \nSelect and explain. \nA. Vit B1, B. Vit B2, C. Vit B3, D. Vit B4', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Transketolase activity is seen in Vit B1. In thiamine deficiency, blood thiamine is reduced, but pyruvate, alpha-ketoglutarate and lactate are increased. Erythrocyte transketolase activity is reduced; this is the earliest manifestation seen even before clinical disturbances. Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 392', 'role': 'assistant'}]