This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Medicine
[{'content': 'First symptom of digoxin overdose is- \nSelect and explain. \nA. GIT disturbance, B. U-vave on ECG, C. Ectopic on ECG, D. Fainting spells', 'role': 'user'}, {'content': 'Answer: A \nExplanation: the first symptom of digoxin overdose is GI disturbance ie nausea and anorexia Ref Davidson 23rd edition pg 460', 'role': 'assistant'}]