<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A previously healthy 42-year-old man is brought to the emergency department 1 hour after he was involved in a motor vehicle collision. He is conscious. He smoked one pack of cigarettes daily for 16 years but quit 8 years ago. Physical examination shows several ecchymoses over the trunk and abdomen. The abdomen is soft, and there is tenderness to palpation of the right upper quadrant without guarding or rebound. Vital signs are within normal limits. An x-ray of the chest shows no fractures; a 10-mm solid pulmonary nodule is present in the central portion of the right upper lung field. No previous x-rays of the patient are available. A CT scan of the chest is performed, which shows that the nodule has irregular, scalloped borders. Which of the following is the most appropriate next step in the management of this patients pulmonary nodule?? A: Antituberculous therapy, B: Positron emission tomography, C: Follow-up chest x-ray in 12 months, D: Follow-up CT scan in 12 months, E: Reassurance,  <response>: This is a question about the appropriate management of a pulmonary nodule found incidentally on a chest x-ray in a 42-year-old man with a history of smoking. The key findings are that the nodule is 10mm in size, solid, located centrally in the right upper lung field, and has irregular scalloped borders on CT scan. The differential diagnosis for a pulmonary nodule includes primary lung cancer, metastatic disease, granulomatous infection, and benign lesions. In this patient with a history of smoking, primary lung cancer is a major concern. The size, location, and irregular borders on CT scan raise suspicion for malignancy. Choice A for antituberculous therapy is not indicated given no evidence of active TB infection. Choice C for follow up chest x-ray in 12 months would be appropriate for a benign-appearing smaller nodule, but not given the suspicious features here. Choice D for follow up CT scan in 12 months may be reasonable depending on the overall clinical context, but more urgent evaluation is warranted given the concern for lung cancer. Choice E for reassurance alone is not sufficient.The most appropriate next step would be choice B, positron emission tomography PET. PET scan can help differentiate malignant from benign nodules and guide biopsy if indicated. Tissue diagnosis should be pursued given the concern for lung cancer.B: Positron emission tomography 