When the Double Extension Approach to the Dollar-Value LIFO Inventory

When the double extension approach to the dollar-value LIFO inventory cost flow method is used, the inventory layer added in the current year is multiplied by an index number.How would the following be used in the calculation of this index number?

$\begin{array}{ll} &\text { Ending inventory}& \text { at current year cost}\\&\text { Ending inventory}& \text { at base year cost}\\ \hline\end{array}$

A) $~~~~~~~~$ Numerator $~~~~~~~~$$~~~~~~~~$$~~~~~~~~$ Denominator
B) $~~~~~~~~$ Numerator $~~~~~~~~$$~~~~~~~~$$~~~~~~~~$ Not used
C) $~~~~~~~~$ Denominator $~~~~~~~~$$~~~~~~~~$$~~~ ~ ~$ Numerator
D) $~~~~~~~~$ Not used $~~~~~~~~$$~~~~~~~~$$~~~~~~~~~~$ Denominator