Assertion (A) : Out of $[\text{Co}(\text{en})_3]^{3+}$ and $[\text{Co}(\text{CN})_6]^{3-}$, coordination compound $[\text{Co}(\text{en})_3]^{3+}$ is a more stable complex. Reason (R) : Ethane-1,2-diamine is a chelating ligand.