Is following statement is true or false and explain why you think so.

a) In perfectly competitive market, the long-run supply curve is downward sloping in decreasing cost industry

b)The marginal revenue for a perfectly competitive firm is equal to the market price. The marginal revenue for a monopolist is greater than the market price for positive quantities of output.

c)Assume that the monopolist's marginal cost is positive at all level of output. The monopolist always produces in the elastic region o the demand curve.