<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 34-year-old woman presents to the physician because of fever and sore throat for 2 days. She also reports generalized body pain and fatigue over this period. She was diagnosed with Graves disease 6 months ago. Because of arthralgias and rash due to methimazole 3 months ago, her physician switched methimazole to PTU. She appears ill. The vital signs include: temperature 38.4C 101.1F, pulse 88min, respiratory rate 12min, and blood pressure 12080 mm Hg. A 1 × 1 cm ulcer is seen on the side of the tongue and is painful with surrounding erythema. Examination of the neck, lungs, heart, and abdomen shows no abnormalities. She had normal liver aminotransferases last week. Which of the following is the most important diagnostic study at this time?? A: Alanine aminotransferase, B: Complete blood count with differential, C: Erythrocyte sedimentation rate, D: Thyroid-stimulating hormone, E: No further testing is indicated,  <response>: This is a patient with Graves disease who recently switched from methimazole to PTU due to side effects. She now presents with fever, sore throat, body aches, fatigue, and a tongue ulcer. The main diagnostic consideration is agranulocytosis secondary to PTU use. Therefore, the most important diagnostic test would be a complete blood count with differential to check for neutropenia or leukopenia. Thyroid function tests are less relevant in this acute setting. Liver enzymes may be indicated to monitor for hepatotoxicity but are not the most urgent test needed. ESR is a non-specific marker of inflammation. No further testing is not an appropriate option given her concerning symptoms.B: Complete blood count with differential 