You are answering a USMLE-style medical question. Question: A 16-month-old boy is brought to the physician by his mother for a regular check-up. His mother says that he has not yet begun to walk. He is exclusively breastfed. He is at the 20th percentile for length, 10th percentile for weight, and 50th percentile for head circumference. Physical examination shows erosion of the enamel on the lingual surface of the incisors and carious molars. He has frontal bossing. His wrists are widened, his legs appear bowed, and there is beading of the ribs. Which of the following is the most likely underlying cause of this patient's condition? Options: A) Deficiency of cofactor for prolyl and lysyl hydroxylase B) Defect in type I collagen C) Impaired growth plate mineralization D) Mutation of fibroblast growth factor receptor 3 Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.