Which of the following expressions represents the molar conductivity of an electrolyte of type $A_2B_3$?

• A
  $2 \lambda_{A^{3+}}^0 + 3 \lambda_{B^{2-}}^0$
• B
  $3 \lambda_{A^{2+}}^0 + 2 \lambda_{B^{3-}}^0$
• C
  $2 \lambda_{A^{3+}}^0 + 3 \lambda_{B^{2-}}^0$
• D
  $1 \lambda_{A^{6+}}^0 + 3 \lambda_{B^{2-}}^0$