the marginal cost of the fourth unit is____

How can marginal cost be expressed mathematically? Marginal cost (MC) can be expressed as O A. MC=TC -FC, where TC is total cost and FC is fixed cost. B. ATC MC = AQ : where TC is total cost and Q is output. O C. MC = AAC AO : where AC is average cost and Q is output. O D. MC = TC : where TC is total cost and Q is output. O E. MC = AFC AQ : where FC is fixed cost and Q is output. For example, if the total cost of producing three units of output is $2,616 and the total cost of producing four units of output is $3,322, then the marginal cost of the fourth unit is $ . (Enter your response as an integer.)