The following diagram shows the market demand for widgets and the associated marginal revenue curve. When the industry is monopolized, the marginal cost curve is MCM. When the industry is competitive, the industry’s marginal cost curve is MCC. Suppose the industry is currently monopolized and you are a judge with the power to break up the monopoly into several competing firms. In order to exercise that power to improve economic efficiency, which four of the labelled areas would you want to measure?