Answer: b. Marginal revenue is less than average revenue
Explanation:
Marginal revenue is the extra revenue received by selling one more unit of a good while Average revenue is the revenue generated on average by all units sold thus far.
If the monopolist has to reduce prices to sell more goods then it would mean that for every unit sold, the price would have reduced compared to the price of the last unit which translates to less revenue coming in per unit compared to the last unit.
On the other hand, on average, the higher prices of the earlier goods sold would keep the average revenue higher than the additional revenue (marginal revenue).
