The following is an extract of a cost report for Malvern Bakery (MB) for three months from March to May. Management considers the activities in the MB business are within the relevant range for the purpose of cost estimation.

Month	Machine Hours	Energy cost
March	140	$7,850
April	175	$9,200
May	160	$8,900

The energy cost is a:

Select one:

a. Step-fixed cost

b. Variable cost

c. Fixed cost

d. Semi-variable (or mixed) cost