The correct answer is B. variable cost.
A variable cost is a cost that changes in proportion to the level of production. For example, the cost of raw materials is a variable cost, because the more products you produce, the more raw materials you will need to purchase.
A fixed cost is a cost that does not change in proportion to the level of production. For example, the cost of rent is a fixed cost, because you will have to pay rent regardless of how many products you produce.
A total cost is the sum of all the variable and fixed costs.
An infeasible cost is a cost that is not possible to achieve. For example, if you are trying to produce a product with zero cost, this would be an infeasible cost.
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