In the field of inorganic chemistry, which statement correctly describes the use and significance of the Tanabe-Sugano diagrams for transition metal complexes? A) Tanabe-Sugano diagrams are primarily used to predict the magnetic properties of transition metal complexes, irrespective of their ligand field strength. B) These diagrams provide a visual representation of the energy levels of d-orbitals under a crystal field, used for predicting the electronic spectra and color of transition metal complexes. C) Tanabe-Sugano diagrams are applicable exclusively to octahedral complexes with d^0 or d^10 electron configurations and are used to determine their geometric distortions. D) The diagrams are used to illustrate the reaction mechanisms of transition metal complexes, showing the pathways of ligand substitution and redox reactions.