Answer:
d. Hi-Tech's marginal-cost curve shifts downward
Step-by-step explanation:
In the event where Hi Tech prevents other other firms from using the new technology which sharply reduces the cost of printing books. Hi Tech's marginal-cost curve shifts downward.
Marginal cost can be defined as the additional cost incurred for the production of an additional unit of output. The formula is calculated by dividing the change in the total cost by the change in the product output.