Answer: a. the former will earn zero economic profits, but the latter will earn positive economic profits.
Step-by-step explanation:
In the long-run, conditions are different for Monopolies and Perfectly competitive firms.
In the long -run, a Perfectly competitive firm would see no economic profits due to the low barriers to entry in the market which will see companies coming into the market and increasing competition to a point where no single firm can make an economic profit.
With a Monopoly though, they are the single supplier in the market and as such will make economic profits in the long run from charging consumers are a rate higher than their marginal cost. As they are the only or major ones in the market, the price will not be challenged leading to an economic profit.
If a perfectly competitive firm and a Monopoly had the same demand and cost curves, the Perfect competition firm would make less as their cost curves would be close or at the same level with the demand but the cost curves would be less than demand for the Monopoly leading to economic profits.