This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urology, Subject name: Anatomy
[{'content': 'Which of the following is not an appropriate investigation for anterior urethral stricture - \nSelect and explain. \nA. High frequency ultrasound, B. Micturating cystourethrogram, C. Retrograde urethrogram, D. Magnetic Resonance Imaging', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Radiological studies in urethral stricture -- (1) Retrograde urethrography - It is the mainstay of radiographic investigation of stricture disease (2) Voiding cystourethrogram / Maturating cystourethrogram MCU demonstrates the segment of urethra proximal to the stricture. (3) Endoscopy Retrograde urethroscopy Antegrade cystrourethroscopy (4) Sonographic urethrogram MRI has no role in the diagnosis of urethral strictures.', 'role': 'assistant'}]