Selected Information About Buehler Corporation's Operations at High and at Low

Selected information about Buehler Corporation's operations at high and at low levels of activity follow:
$\begin{array}{|l|r|r|}\hline &{\text { Level of Activity }} \\\hline & \text { Low } & \text { High } \\\hline \text { Number of Units Produced } & 25,000 & 30,000 \\\hline \text { Total manufacturing } & \$ 575,000 & \$ 680,000\\\text { overhead costs }\\\hline \text { Direct material cost per unit } & \$ 5 & \$ 5 \\\hline \text { Direct labour cost per unit } & \$ 6 & \$ 6\\\hline\end{array}$
Using the high-low method,what is the total variable cost per unit of product?

A) $11.05.
B) $21.00.
C) $32.00.
D) $35.00.