The alkene ligand ($$\pi\text{-C}_2\text{R}_4$$) is both a sigma donor and a pi acceptor, similar to the CO ligand in metal carbonyls, and exhibits synergic bonding with metals. Correct order of C-C bond length in $$\text{K}[\text{PtCl}_3(\pi\text{-C}_2\text{R}_4)]$$ complexes in which R = H, F or CN is

A

H > F > CN

B

H > CN > F

C

CN > F > H

D

F > H > CN