如图所示的二叉排序树，，起查找成功时的平均查找长度是。<img src="https://static.zxtiku.com/wangke/imgs/topic/0f497062ecfa1ba827fc85d0dc1adf94.jpg"/><br/> A、<img src="https://static.zxtiku.com/wangke/imgs/topic/ff372dfc760c9ede7269544e2cc3ec29.jpg"/><br/> B、<img src="https://static.zxtiku.com/wangke/imgs/topic/943f26ffe9fbf2bba5de1947904384a3.jpg"/><br/> C、<img src="https://static.zxtiku.com/wangke/imgs/topic/359f2d0d5d4e221fa2bf8cc15313d5de.jpg"/><br/> D、<img src="https://static.zxtiku.com/wangke/imgs/topic/c8542e2d9e9114fbd5700951ec8e7b62.jpg"/>