—Thanks for your help, but can you do me one more favor, please?

—________, Sir．What’s it then?

A．Just a minute

B．My pleasure

C．That’s right

D．At your service

有瘘管的患牙，行根尖刮治或根尖切除术，行桩冠修复前，需观察（）

A.1周

B.2周

C.3周

D.4周

E.5周