The speaker's reason for changing his opinion was highly pertinent.

A．imaginative

B．unrealistic

C．relevant

D．controversial

男，25岁。诊断左肾结核，右输尿管结石，直径0.8cm，静脉紧盂造影，左肾未显示，右肾轻度积水，结石下输尿管显示正常，肾功检查正常，宜先行哪种治疗

A．切除左肾

B．引流右肾积水

C．急行右输尿管切开取石

D．抗痨下，等待结石自然排出

E．抗痨下，输尿管结石体外震波碎石治疗