If a monopoly becomes perfectly competitive, then Blank______. Multiple choice question. price and quantity both fall, with the monopoly's marginal cost curve now the perfectly competitive supply curve. price and quantity both rise, with the monopoly's marginal revenue curve now the perfectly competitive demand curve. price falls and quantity rises, with the monopoly's marginal cost curve now the perfectly competitive supply curve. price rises and quantity falls, with the monopoly's marginal revenue curve now the perfectly competitive demand curve