一根固定在某两点之间的弦线振动形成驻波时，其基频<img src="https://static.zxtiku.com/wangke/imgs/topic/a3caef76aa0d6b19c85499e7aaa79c31.jpg"/>与二次谐频<img src="https://static.zxtiku.com/wangke/imgs/topic/d76f1a77bc0d3dd5bb0617e7394fded8.jpg"/>之间的关系为（） A. <br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/cf7d28964c3563b78d14d6f119058bac.jpg"/> B. <br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/2478d4a135e18068202bebcc377a1091.jpg"/> C. <br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/d4bd888633f383bbbb2d144abaeea407.jpg"/> D. <br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/f5235c8717a6e58e976d12d3a0971378.jpg"/>