the train was two hours late,so we ( ) have run all the way to the railway station

题目

the train was two hours late,so we ( ) have run all the way to the railway station
A wouldn't
B couldn't
C mustn't
D needn't
但我理解不了,求中文翻译

答案

火车晚点两个小时,所以我们不需要一路奔向火车站.
needn't