二维经典自由粒子的态密度D(ε)正比于________．<br/> A、<img src="https://static.zxtiku.com/wangke/imgs/topic/b6be4c3cfdfb72b2312f8ebc1ab8ca00.jpg"/><br/> B、<img src="https://static.zxtiku.com/wangke/imgs/topic/62f38e466a2bcafd9b4b1f78d28169a5.jpg"/><br/> C、<img src="https://static.zxtiku.com/wangke/imgs/topic/1ddd1cde577e1b939a1807025e387f47.jpg"/><br/> D、<img src="https://static.zxtiku.com/wangke/imgs/topic/b3a95310ba334a9cfa81e1307abd083f.jpg"/>