The correct answer is: A. MC
The vertical difference between TVC and TC is equal to marginal cost (MC). This is because MC is the additional cost incurred by producing one more unit of output. TVC is the total variable cost, which is the total cost of producing a given quantity of output that varies with the quantity of output produced. TC is the total cost, which is the total cost of producing a given quantity of output that includes both variable and fixed costs.
AVC is average variable cost, which is the variable cost per unit of output. TFC is total fixed cost, which is the cost of production that does not vary with the quantity of output produced.
Here is a diagram that illustrates the relationship between MC, TVC, and TC:
[Diagram of a graph with three curves: MC, TVC, and TC. MC is the curve that is closest to the horizontal axis, TVC is the curve that is in the middle, and TC is the curve that is farthest from the horizontal axis.]
As you can see, MC is the curve that is closest to the horizontal axis. This is because MC is the additional cost incurred by producing one more unit of output. TVC is the curve that is in the middle. This is because TVC is the total variable cost, which is the total cost of producing a given quantity of output that varies with the quantity of output produced. TC is the curve that is farthest from the horizontal axis. This is because TC is the total cost, which is the total cost of producing a given quantity of output that includes both variable and fixed costs.
The vertical difference between TVC and TC is equal to MC. This is because MC is the additional cost incurred by producing one more unit of output. TVC is the total variable cost, which is the total cost of producing a given quantity of output that varies with the quantity of output produced. TC is the total cost, which is the total cost of producing a given quantity of output that includes both variable and fixed costs.