An iodine-based electrolyte contains the triiodide ion, \(\text{I}_3^{-}\). Each iodine atom contributes seven valence electrons, and the negative charge contributes one additional electron. Which diagram is the best Lewis representation of \(\text{I}_3^{-}\), accounting for all valence electrons, allowing an expanded valence shell on the central iodine atom, and using the most favorable formal-charge arrangement?