The edge lengths of the unit cells in terms of the radius of spheres constituting fcc, bcc and simple cubic unit cell respectively
A. `2sqrt(2r),(4r)/(sqrt(2)),2r`
B. `(4r)/sqrt(3),2sqrt(2)r,2r`
C. `2r,2sqrt(2r),(4r)/sqrt(3)`
D. `2r,(4r)/sqrt(3),2sqrt(2)r`
