Marginal cost is the change in total cost as a result of increasing output by one unit
Marginal cost = Δcost / Δquantity
0.2 / 0.25 = 0.8
The marginal cost would decrease because the change in output is higher than the change in total cost
Marginal benefit would increase
Opportunity cost is the cost of the opportunity forgone when one alternative is chosen over other alternatives. There is no enough information given to determine the impact on opportunity cost
