函数<img src="https://zk.995w.com/lqwvjeImg/88/883f470a13504d990e649a8805aaa93f.png"style="width:140px;height:24px;">在点<img src="https://zk.995w.com/lqwvjeImg/46/4643b272fa7a474555fdfd7735f36f11.png"style="width:48px;height:20px;">处的最大方向导数为( )。<img src="https://zk.995w.com/lqwvjeImg/49/4961d6c2bb8f75169a36db60b933f0b6.png"style="width:24px;height:18px;"><img src="https://zk.995w.com/lqwvjeImg/73/73497d50977469b0b4f92ee9741a2da3.png"style="width:8px;height:17px;"> <img src="https://zk.995w.com/lqwvjeImg/88/886e3067847fbbbdeddad27e1c6e2c32.png"style="width:24px;height:18px;"><img src="https://zk.995w.com/lqwvjeImg/7c/7cdceaaabe7988349206184a38348b6d.png"style="width:20px;height:17px;"> <img src="https://zk.995w.com/lqwvjeImg/25/25fa0524dca219647f451ea62fc28138.png"style="width:24px;height:18px;"><img src="https://zk.995w.com/lqwvjeImg/45/451c87c8ce840681a66cda8837c4e451.png"style="width:13px;height:19px;"> D. <img src="https://zk.995w.com/lqwvjeImg/72/72b9d1ad9a841538ae830dddf2930d17.png"style="width:25px;height:23px;"><br>·1<br>·-1<br>·0<br>·<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/1697424327420f70cfade86cc42fabae57036f6dd650fimage94.png"