When a monopolist produces 60 units, the total cost of production is $1,200 . When a monopolist produces 70 units, the total cost is $1,400 .

a) When a monopolist produces 80 units, the total cost will be $1,600.
b) When a monopolist produces 50 units, the total cost will be $1,000.
c) When a monopolist produces 65 units, the total cost will be $1,300.
d) When a monopolist produces 75 units, the total cost will be $1,450.