In a market for a homogeneous good, if sellers and buyers can enter or exit a market freely, the market is most likely:

A restriction on imports is likely to reduce further restrictions on trade

Indicate whether the statement is true or false

Suppose a single-price monopoly sells 3 units of a good at $20 per unit. If the monopoly sells 4 units, the total revenue increases to $72. What is the marginal revenue of the fourth unit?

A) $52 B) $18 C) $60 D) $12 E) $20