St John's Company Incurred the Following Costs for the Months

St. John's Company incurred the following costs for the months of March and April.
$\begin{array}{lrr}\text { Type of Cost } &\text { March }&\text { April }\\\text { Insurance } & \$ 5,000 & \$ 5,000 \\\text { Utilities } & 4,000 & 5,000 \\\text { Depreciation } & 3,500 & 3,500 \\\text { Materials } & 10,000 & 20,000\end{array}$
-Refer to the Figure.If output was 5,000 units in March and 10,000 units in April,which of the following can be assumed?

A) Utilities and materials are variable costs.
B) Utilities, insurance, and depreciation are fixed costs.
C) Insurance and depreciation are mixed costs.
D) Materials are the only variable cost.