Progress so far has been very good.        , we are sure that the project will be completed on time.[      ]

A. However        

B. Otherwise    

C. Therefore    

D. Besides

病历摘要：患者男性，38岁，间歇性无痛性全程肉眼血尿1天。血尿呈洗肉水样，无血块。无尿频、尿急和尿痛。无排尿费力。无腰痛。平素健康。体检：双肾区无叩击痛，双侧输尿管行程无压痛，耻骨上区无膨隆和压痛。

何时开始膀胱灌注丝裂霉素效果最好？（）

A.手术结束时

B.术后1周

C.术后2周

D.术后3周

E.术后4周