The Phone Bill for a CPA Firm Is a Mixed

Multiple Choice

The phone bill for a CPA firm is a mixed cost. Please refer to the 4-month data below, apply the high-low method, and answer the question.
$$\begin{array} { | l | r | r | } \hline & { \text { Minutes } } & \text { Total Bill } \\\hline \text { Jan } & 300 & \$ 2,650 \\\hline \text { Feb } & 150 & \$ 2,575 \\\hline \text { Mar } & 100 & \$ 2,550 \\\hline \text { Apr } & 250 & \$ 2,625 \\\hline\end{array}$$
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How much is the variable cost per minute?

A) $0.50
B) $1.75
C) $2.50
D) $0.25