<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 50-year-old man comes to the physician because of diffuse weakness for the past several months. There is an anterior mediastinal mass on a lateral x-ray of the chest that was performed as part of a pre-employment medical evaluation. He has gastroesophageal reflux disease. His only medication is rabeprazole. He is 178 cm 5 ft 10 in tall and weighs 77 kg 170 lb; BMI is 24.3 kgm2. Vital signs are within normal limits. There is no cervical or axillary lymphadenopathy. Cardiopulmonary examination shows no abnormalities. The abdomen is soft and nontender; there is no splenomegaly. Further evaluation of this patient is most likely to show which of the following?? A: Fever, night sweats, and weight loss, B: Elevated serum alpha-fetoprotein level, C: Acetylcholine receptor antibodies, D: Elevated TSH and a nodular anterior cervical mass, E: Increased urinary catecholamines,  <response>: This is a clinical vignette describing a 50-year-old man with diffuse weakness, anterior mediastinal mass on chest x-ray, and gastroesophageal reflux disease. The key findings are the anterior mediastinal mass and diffuse weakness. The choices describe findings that may be seen with different types of anterior mediastinal masses:A Fever, night sweats and weight loss - LymphomaB Elevated serum alpha-fetoprotein - Germ cell tumor C Acetylcholine receptor antibodies - ThymomaD Elevated TSH and anterior cervical mass - Thyroid massE Increased urinary catecholamines - Neuroendocrine tumorBased on the clinical vignette, the most likely diagnosis is a thymoma given the anterior mediastinal mass and muscle weakness. Thymomas are associated with acetylcholine receptor antibodies and myasthenia gravis.C: Acetylcholine receptor antibodies 