一平面简谱横波的波动表达式为y=0.05cos（20πt+4πx）（SI），取k=0，±1，±2，…。则t=0.5s时各波峰所在处的位置为（　　）。

A、<img width="78" height="33" src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/839dadca-6f9d-46b0-9831-56f78b7bc3fb.png" />

B、<img width="71" height="33" src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/b3e4efc4-55ec-4288-a1d7-02c61c572842.png" />

C、<img width="71" height="35" src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/e679ab58-76cc-43e4-95eb-cf67111f50a3.png" />

D、<img width="63" height="33" src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/74d68d06-c77b-4ed1-a01c-f80401beb770.png" />

A、<img width="76" height="33" id="图片 1295" src="http://admintk.100xuexi.com/UpLoadImage/2016-10-26/80c909e5-b232-48e5-a3e8-a90b2aab17fa.png" />

B、<img width="71" height="34" id="图片 1297" src="http://admintk.100xuexi.com/UpLoadImage/2016-10-26/d539707f-1c83-4fdb-812b-30256cad1ca9.png" />

C、<img width="73" height="35" id="图片 1298" src="http://admintk.100xuexi.com/UpLoadImage/2016-10-26/e6ba43fa-4096-4627-bb61-6124193aee7e.png" />

D、<img width="59" height="33" id="图片 1300" src="http://admintk.100xuexi.com/UpLoadImage/2016-10-26/70fef648-949d-4c3a-ac8b-b4ce48566094.png" />