<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 29-year-old G1P0 at 23 weeks of gestation presents to the ED for left flank pain migrating to the groin. The pain is sharp, causing her to have nausea and vomiting. She also endorses urinary frequency, but denies vaginal discharge. There have been no complications in her pregnancy thus far. Her abdominal exam is remarkable for left lower quadrant tenderness to palpation with pain radiating to the left groin, but no guarding. She also has tenderness to palpation of the left flank. Blood is visible on inspection of the perineal area.Urinalysis:Urine Color: YellowpH: 7.1Specific gravity: 1.010Blood: 3Bilirubin: NegativeGlucose: NegativeKetones: NegativeProtein: NegativeNitrite: NegativeLeukocyte esterase: NegativeRed blood cells: 291 cellsulWhite blood cells: 75 cellsulWhich of the following is the next best step in management?? A: Renal radiograph, B: Intravenous pyelogram, C: Renal ultrasound, D: Noncontrast CT scan of abdomen and pelvis, E: Exploratory laparoscopy,  <response>: This is a case of a pregnant woman in her second trimester presenting with left flank pain radiating to the groin, nausea, vomiting, urinary frequency, and hematuria. The key findings in the history and physical exam are left lower quadrant tenderness and flank tenderness concerning for possible kidney stone or infection. The urinalysis shows hematuria and pyuria concerning for urinary tract infection. The next best step in management would be to do imaging to evaluate for kidney stone versus pyelonephritis. Renal ultrasound would be the preferred initial imaging modality in pregnancy given the risks of radiation exposure to the fetus with other studies like CT. Renal radiograph and IVP would not provide adequate assessment of the kidney and surrounding structures. Exploratory laparoscopy would be overly invasive as initial management.C: Renal ultrasound 