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: Surgery
[{'content': 'The most impoant use of transrectal ultarsonography (TRUS) is for \nSelect and explain. \nA. Screening for Ca prostate, B. Distinguishing prostate cancer from BPH, C. Systematic prostate biopsy in suspected prostate cancer, D. Guiding transurethral resection of prostate cancer', 'role': 'user'}, {'content': 'Answer: C \nExplanation: A transrectal ultrasound (TRUS) may also be called endorectal ultrasound. It is used to look at the prostate and tissues around it. A TRUS is often used to help diagnose prostate cancer if the prostate-specific antigen (PSA) level is high, or an abnormal area during a digital rectal exam (DRE) . TRUS is done to: look at the size and shape of the prostate look for abnormal areas in the prostate guide a needle during a biopsy to collect samples from the prostate " TRUS technology has become a mainstay of many image guided prostate interventions, including prostate biopsy, brachytherapy, cryotherapy, and high-intensity focused US " Campbell and walsh 11th edition', 'role': 'assistant'}]