This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Physiology
[{'content': 'Albinism is due to: \nSelect and explain. \nA. Marked deficiency of melanin pigment, B. Thymus disorder, C. Tumour of pineal gland, D. ACTH deficiency', 'role': 'user'}, {'content': 'Answer: A \nExplanation: deficiency of melanin pigment results in a marked deficiency of pigment in eyes, hair and skin Ref: guyton and hall textbook of medical physiology 12 edition page number: 550,551,552', 'role': 'assistant'}]