You are answering a USMLE-style medical question. Question: A 19-year-old Caucasian male presents to your office with hypopigmented skin. He undergoes a skin biopsy and is found to have an absence of melanocytes in the epidermis. Which of the following is the most likely diagnosis? Options: A) Tinea versicolor B) Albinism C) Vitiligo D) Melanoma Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.