Final answer:
The difference between total cost and total variable cost curves is the fixed costs, which remain constant as output changes, making the vertical distance between these curves constant as well.
Step-by-step explanation:
The question is asking about the difference between total cost (TC) and total variable cost (TVC) as output increases. The TC curve includes both variable and fixed costs, with fixed costs being a constant amount that does not vary with the level of output. At zero output, there are no variable costs, thus the TC curve starts at the level of the fixed costs. As output increases, TC and TVC both increase because you need to spend more on variable inputs like labor and raw materials. However, the fixed costs stay constant regardless of the level of output.
Therefore, the vertical distance between the TC and TVC curves represents the fixed costs, which remains constant as output changes. Hence, option B is correct, as the vertical distance between the total cost and the total variable cost curves is constant as output changes.