单选题 She didn"t tell the reason ______ she was absent from the important lecture.
【正确答案】 D
【答案解析】[解析] 本题考查定语从句引导词。定语从句中，reason作先行词，而且空格后的句子不缺主语和宾语，则从句一般用why引导，故正确答案为选项D。