单选题
[2009.10]The traffic was held up for more than thirty minutes，______ caused me to arrive late.
A.it
B.that
C.what
D.which
正确答案：D
答案解析：本题考查非限制性定语从句。整句话的意思是：交通阻塞30多分钟，这使得我到达晚了。