The Following Information Is Available for Maintenance Costs -Refer to the Figure

Multiple Choice

The following information is available for maintenance costs:
$$\begin{array} { l c c } \text { Month } & \text { Production Volume } & \text { Maintenance Costs } \\\hline\text { January } & 75 & \$ 250 \\\text { February } & 115 & 310 \\\text { March } & 190 & 400 \\\text { April } & 60 & 240 \\\text { May } & 135 & 355\end{array}$$
-Refer to the figure.Using the method of least squares,what would the variable cost per unit of production be (rounded to two decimal places) ?

A) $1.23
B) $1.31
C) $2.70
D) $3.21