<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 35-year-old man comes to the physician because of worsening pain in his lower back, knees, and shoulders over the past few years. He used to be able to touch his fingers to his toes while standing; now he has difficulty touching his shins. He is wearing a shirt with dark brown stains around the armpits. Physical examination shows bluish-brown sclerae and thickening of the external ear. The range of motion of the affected joints is decreased. X-rays of the spine show calcification of multiple lumbar intervertebral discs. The patients condition is most likely caused by impaired metabolism of which of the following?? A: Homocysteine, B: Tryptophan, C: Hypoxanthine, D: Tyrosine, E: Ornithine,  <response>: This is a clinical vignette describing a 35-year-old man with progressive joint pain and decreased range of motion in his lower back, knees and shoulders over the past few years. Key findings include dark brown stains around his armpits, bluish-brown sclerae, thickened external ears, decreased joint mobility, and calcification of lumbar discs on X-ray. This constellation of findings is most consistent with alkaptonuria, a rare inherited disorder of tyrosine metabolism caused by deficiency of homogentisic acid oxidase. This results in accumulation of homogentisic acid which gets deposited in connective tissues, leading to the characteristic findings of ochronosis and eventual joint damage. Of the answer choices, tyrosine metabolism is impaired in alkaptonuria, making choice D the most likely answer. The other amino acids are not directly implicated in this disorder.D: Tyrosine 