一只蚂蚁从下图的正方体A顶点沿正方体的表面爬到正方体C顶点，设正方体边长为a，问该蚂蚁爬过的最短路为（　　）。

A、<img width="93" height="49" src="http://admintk.100xuexi.com/UpLoadImage/2016-08-19/1482bcdb-f59a-470b-9b6f-b9ed68593673.png" />

B、<img width="27" height="26" src="http://admintk.100xuexi.com/UpLoadImage/2016-08-19/87bcef49-34ed-4c9b-be20-6c961a6be244.png" />a

C、（1＋<img width="24" height="23" src="http://admintk.100xuexi.com/UpLoadImage/2016-08-19/bebdc230-fce0-4c96-8019-72b8d904efe3.png" />）a

D、（1＋<img width="26" height="25" src="http://admintk.100xuexi.com/UpLoadImage/2016-08-19/eebb5546-6eef-48a1-a534-c65ca04d90c4.png" />）a