对出入境旅客携带物品，现场检疫不能得出结果的，需要截留作实验室检验以及现场检疫认为必须作除害处理的，则作截留处理，检疫员签发《出入境人员携带物留检/处理凭证》交给物主。

The students in Class Two always exercise a lot. ______ homework, they finish it very quickly.                [ ]

A. To        

B. As for        

C. As          

D. Because of