It may be concluded that at this monthly output rate, marginal revenue is A) $5 per unit, and the monopolist earns zero economic profits.
B) $6 per unit, and the monopolist earns economic profits of $2,000 per month.
C) $6 per unit, and the monopolist earns economic losses of $1,000 per month.
D) $6 per unit, and the monopolist earns economic profits of $3,000 per month.