函数<img src="null"/>的最大值为( )<br/> A、<img src="https://static.zxtiku.com/wangke/imgs/topic/d2f24da445558cb40756c7c784483cb3.png"/><br/> B、<img src="https://static.zxtiku.com/wangke/imgs/topic/362bd0f24d9f8fbd5092ac008e67a6ca.png"/><br/> C、<img src="https://static.zxtiku.com/wangke/imgs/topic/13c5f19a161eeb7084a823e36f808fe4.png"/><br/> D、<img src="https://static.zxtiku.com/wangke/imgs/topic/07a41e1ef64b2013f44611ad138298dc.png"/>