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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