生成这个题目的讲解---**Question 9**
**Question Stem:**
已知球O的半径为1, 四棱锥的顶点为O, 底面的四个顶点均在球O的球面上, 则当该四棱锥的体积最大时, 其高为 ( )
*(Translation: Given that the radius of sphere O is 1, the apex of a quadrangular pyramid is O, and the four vertices of its base are all on the surface of sphere O. When the volume of this quadrangular pyramid is maximized, what is its height?)*
**Options:**
A. 1/3
B. 1/2
C. √3/3
D. √2/2