The correct answer is A. fixed cost.
A fixed cost is a cost that does not change with the level of production. This means that even if you produce more or less, the fixed cost will stay the same. Some examples of fixed costs include rent, insurance, and salaries.
A constant cost is a cost that changes with the level of production, but at a constant rate. This means that if you produce twice as much, the constant cost will also double. Some examples of constant costs include materials and utilities.
A variable cost is a cost that changes with the level of production, but at a non-constant rate. This means that if you produce twice as much, the variable cost will not double. Some examples of variable costs include labor and shipping.
In conclusion, the correct answer is A. fixed cost. This is because a fixed cost does not change with the level of production.