（ ） you didn't confirm the offer within its validity, we sold th

（ ） you didn't confirm the offer within its validity, we sold the goods to other clients.
A、When
B、Although
C、Since
D、Where
【正确答案】：C
【题目解析】：因为你没有在有效期内接受邀请， 我们已经将货物卖给其他用户了。