Costs necessary to effect a one-unit increase in the activity level is a A. Differential cost. B. Opportunity cost. C. Marginal cost.

Marginal Cost is the answer..........................

marginal cost is the correct answer

C is the answer.

The cost which make increase in production is called marginal cost.

Option (B) is my pick for the answer

Answer option >>>>>>>>>>>   C. Marginal cost.

C. Marginal cost. ...........................