Answer:
As a firm produces more of a good, the cost of producing each additional unit INCREASES. This implies that the marginal cost of producing a good INCREASES as you make more of that good.
Explanation:
Marginal production costs are the additional costs of producing one additional unit of output.
Generally if you follow a normal production cost curve, the marginal costs at first tend to decrease since both average variable costs and fixed costs decrease. But after a while, variable costs tend to increase (higher marginal costs) and they offset the decrease in average fixed costs.