This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Medicine
[{'content': 'What is the most likely cause of this presentation? \nSelect and explain. \nA. Chemotherapy, B. Hyperthyroidism, C. Nephrotic syndrome, D. Psoriasis', 'role': 'user'}, {'content': "Answer: A \nExplanation: Answer A. ChemotherapyThese multiple white lines on the fingernails, known as Beau's lines, correspond with chemotherapy cycles in this patient with gastric cancer. Cytotoxic chemotherapeutic agents can induce the temporary arrest of proliferative function of the nail matrix.", 'role': 'assistant'}]