On the top of a hemispherical done of radius r, there stands a flag of height h. From a point on the groung, the elevation of the top of the flag is `30^(@)`. After moving a distance d towards the done, when the flag is just visible, the elevation is `45^(@)`. The ratio of h to r is equal to

Options

A. `sqrt(2)-1`
B. `(sqrt(3)+1)/(2sqrt(2))`
C. `(sqrt(3)+1)/(2sqrt(2))d`
D. `((sqrt(3)+1)(sqrt(2)-1))/(2sqrt(2))d`