n级m序列的周期为______<br/> A、<img src="https://static.zxtiku.com/wangke/imgs/topic/9ebc7039175182f8f41ecaa0b0159d3c.jpg"/><br/> B、<img src="https://static.zxtiku.com/wangke/imgs/topic/c4a50437b66dd2770cd52a6d0323dec8.jpg"/><br/> C、<img src="https://static.zxtiku.com/wangke/imgs/topic/7d3cd9cf8b468232ebe7b90bd0a96293.jpg"/><br/> D、<img src="https://static.zxtiku.com/wangke/imgs/topic/4fe9e08d53eb845aed87e3f2de8cc02f.jpg"/>