设<img src="https://static.zxtiku.com/wangke/imgs/topic/c6eb3bd8b1b373be2fb7eaea234fbdfe.jpg"/>,<img src="https://static.zxtiku.com/wangke/imgs/topic/152c298f9014aa85250826f78239c41e.jpg"/>的长度分别为9和5，他们的DFT结果分别为<img src="https://static.zxtiku.com/wangke/imgs/topic/40b5913b661e797570cedf5d1f3c4122.jpg"/>和<img src="https://static.zxtiku.com/wangke/imgs/topic/327e1c86b6bd38976aec8198ccf70fd5.jpg"/>则两序列的时域序列的DFT之积结果为（）。 A. <br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/3d57f7beb63278b6c1939fab0d5a1074.jpg"/> B. <br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/16bc596711a10d2862ab2b579159ef3e.jpg"/> C. <br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/7f6bdf57ed523a519118aa4804273379.jpg"/> D. <br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/3d793ecbd91a676396c6b94d1ac760fd.jpg"/>