Which statement about the coordination number of a cation is true?

• A
  Most metal ions exhibit only a single characteristic coordination number.
• B
  The coordination number is equal to the number of ligands bonded to the metal atom.
• C
  The coordination number is determined solely by the tendency to surround the metal atom with the same number of electrons as one of the rare gases.
• D
  For most cations,the coordination number depends on the size and charge of the cation.