We had to put the meeting off ( ) so many students were absent

We had to put the meeting off ( ) so many students were absent.
A、unless
B、as far as
C、since
D、though
【正确答案】：C
【题目解析】：考核关联词的含义，根据逻辑关系判断使用原因的。since表示原因，句子含义是因为很多学生缺勤，我们不得不推迟会议。