某有限长线声源的长度为L，在线声源垂直平分线上距离线声源处的声级为，采用近似点声源衰减公式预测垂直平分线上距离线声源r处的噪声级，必须满足的条件是（    ）。

A、<p><img src="http://edu24ol.bs2cdn.100.com/7c3cf99c32bbb5d58b35980eccb34a53a16d8a9a.png" width="20" height="17" title="QQ图片20170512104349.png"/>＞L， r＞L</p>

B、<p>r＜L/3，<img src="http://edu24ol.bs2cdn.100.com/e8e80112ab4779884fe918dc63abdbaf20759a19.png" width="20" height="17" title="QQ图片20170512104349.png"/>＜L/3</p>

C、<p>L/3＜r＜L</p>

D、<p><span style="font-family: \'Microsoft YaHei\'; font-size: 13px; "></span><img src="http://edu24ol.bs2cdn.100.com/fe12fbb0f7bbe5596de64ffcea8d44aae0441c50.png" width="20" height="17" title="QQ图片20170512104349.png"/>＜L，r＞L</p>

D、<p><span style="font-family: 'Microsoft YaHei'; font-size: 13px; "></span><img src="http://edu24ol.bs2cdn.100.com/fe12fbb0f7bbe5596de64ffcea8d44aae0441c50.png" width="20" height="17" title="QQ图片20170512104349.png"/>＜L，r＞L</p>