Marten Company Uses the FIFO Method in Its Process Costing

Marten Company uses the FIFO method in its process costing system.Operating data for the Casting Department for the month of September appear below:
$$\begin{array} { | l | r | r | } \hline & \text { Units } & \text { Percentage complete } \\\hline \text { Beginning work in process } & 19,000 & 80 \% \\ \text { inventory } & & \\\hline \text { Transferred in from the } & 74,000 & \\\text { prior department during } & & \\\text { September } & & \\\hline \begin{array} { l } \text { Ending work in process } \\\text { inventory }\end{array} &17,000 &90\% \\\hline\end{array}$$
According to the company's records,the conversion cost in beginning work-in-process inventory was $83,600 at the beginning of September.Additional conversion costs of $427,682 were incurred in the department during the month.
What would be the cost per equivalent unit for conversion costs for September on the Casting Department's production report? (Round off to three decimal places.)

A) $5.498.
B) $5.779.
C) $5.620.
D) $5.500.