You are answering a USMLE-style medical question. Question: A 17-year-old man presents to his family physician for an evaluation about the size of his penis. He feels increasingly anxious during physical education (PE) class as he has noticed that the size of his penis is significantly smaller when compared to his peers. Based on the physical examination, he is Tanner stage 1. The weight and height are 60 kg (132 lb) and 175 cm (5 ft 9 in), respectively. The cardiopulmonary examination is normal; however, the patient has difficulty identifying coffee grounds by smell. Which of the following explains the pathophysiology underlying this patient’s disorder? Options: A) Expansion of a CTG trinucleotide repeat B) Isolated gonadotropin-releasing hormone (GnRH) deficiency C) Sex-specific epigenetic imprinting D) Non-disjunction of sex chromosomes Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.