Suppose the demand function in the industry is p= 100 - y and each firm has a constant marginal cost of $40 and no fixed costs. If the Cournot model of oligopoly accurately reflects firm behaviour in this industry, then the aggregate equilibrium output of n+ 1 firms can be expressed as:

A)60(n+ 1)/(n+ 2).

B) 160n/(n+ 1).

C)20(n+ 1).

D) 160(n+ 1)/(n+ 2).