Sodium is produced by the electrolysis of a molten mixture of about $40\%$ $NaCl$ and $60\%$ $CaCl_2$ because

• A
  $CaCl_2$ helps in the conduction of electricity
• B
  This mixture has a lower melting point than pure $NaCl$
• C
  $Ca^{2+}$ can displace $Na$ from $NaCl$
• D
  $Ca^{2+}$ can reduce $NaCl$ to $Na$