通过贸易、生产、来料加工、代繁、科研、交换、展览、援助、赠送等各种方式进境的植物繁殖材料须事先办理检疫审批手续，但享有外交、领事特权与豁免权的外国机构的进境植物繁殖材料除外。( )

I was about to __________ the phone when it was _________.  [ ]

A. reply; rung off.    

B. receive; rung up.    

C. answer; rung off.    

D. answer;rung up