题目2单选题
函数<img src="https://tihai-oss-cloud.itihey.com/img/9ac827b689396a986246b7d5a31f79cc.png">的拐点的横坐标为( )A. <img src="https://tihai-oss-cloud.itihey.com/img/a78a8ed50ecfe69aced3ae082a526ee5.png">B. <img src="https://tihai-oss-cloud.itihey.com/img/a4d3754a0ac2a2556bd4cdb4a8e419ff.png">C. <img src="https://tihai-oss-cloud.itihey.com/img/efbf84728ebb555c35e08a9598385912.png">D. <img src="https://tihai-oss-cloud.itihey.com/img/93b14fbfaaadd2ad96bb3c483f2cf07a.png">