英语题 初中：Every morning Mr.Smith takes a ----- to his office. 选

英语题 初中：Every morning Mr.Smith takes a _____ to his office. 选择题!选项见下!
A.20minites' walk B.20 minite's walk C.20-minites walk D.20-minite walk
资料答案是A,我觉得是D,高手指教!