Space Lattice Relation between Atomic Radius r and Edge element a

Question

 Which one of the following pairs is not correctly matched?        

Space Lattice Relation between Atomic Radius r and Edge element a

(a) Simple cubic structure : a² = 4r²

(b) Body-centred cubic structure: 3a² = 16r²

(c) Triclinic : 2a² = 3r²

(d) Face-centred cubic structure : a² = 8r²