although we had told them not to keep us waiting,they made n

选b正确。句子意思：尽管我们已经告诉过他不要让我们等待,但是他们并没有尝试/设法加速交货。选项辨析：a,trial 试验；努力b,attempt 试图；企图；尝试；打算c,action 行动；活动d,progress 进步；进展根据句子意思和词汇用法搭配,有个固定搭配：make an/no attempt to do sth。因此,排除其它选项。祝你开心如意!