Variable costs are costs
a) that vary in total directly and proportionately with changes in the activity level.
b) remain the same per unit at every activity level.
c) neither of these.
d) there are two of the responses that are correct.

Correct option is D

Explanation:

Variable cost remains constant for each single unit.

That means variable cost is defined per unit, therefore with this we know statement b is correct.

Also with change in production in number of units, the total cost varies and proportionately changes with change in level of output.

Therefore statement A is also correct.Thus on the conclusive part, Staement D is correct.

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