There Are Two Firms in the Blastopheme Industry

There are two firms in the blastopheme industry. The demand curve for blastophemes is given by p = 3,000 - 2q. Each firm has one manufacturing plant and each firm i has a cost function C(q_i) = q²_i, where q_i is the output of firm i. The two firms form a cartel and arrange to split total industry profits equally. Under this cartel arrangement, they will maximize joint profits if

A) and only if they each produce a total of 750 units.
B) they produce a total of 500 units, no matter which firm produces them.
C) and only if each firm produces 300 units in its plant.
D) they produce a total of 600 units, no matter which firm produces them.
E) they shut down one of the two plants, having the other operate as a monopoly and splitting the profits.