Problem: a sphere is inscribed in a cube with an edge of 10 . what is the shortest possible distance from one of the vertices of the cube to the surface of the sphere ? 
Options: ['a ) 10 ( √ 3 - 1 )', 'b ) 5', 'c ) 10 ( √ 2 - 1 )', 'd ) 5 ( √ 3 - 1 )', 'e ) 5 ( √ 2 - 1 )']
d