由抛物线<img src="https://static.zxtiku.com/wangke/imgs/topic/9e76bc2bc2917114bef1b0fdf123b8ce.jpg"/>和<img src="https://static.zxtiku.com/wangke/imgs/topic/37ac1d4b53294e0312c2b56bcf748460.jpg"/>所围成的图形绕 y 轴旋转一周而成的旋转体的体积为( )<br/> A、<img src="https://static.zxtiku.com/wangke/imgs/topic/1713c6290f958c0840a847c16dd356fa.jpg"/><br/> B、<img src="https://static.zxtiku.com/wangke/imgs/topic/effead888f1a8c671c2183e18c0d018d.jpg"/><br/> C、<img src="https://static.zxtiku.com/wangke/imgs/topic/596c2f55f7cec468d1720345b32abdf5.jpg"/><br/> D、<img src="https://static.zxtiku.com/wangke/imgs/topic/7316199832f40313ae55f1775e7876b1.jpg"/>