Q. Rule of thumb is that, IF demand and supply curves incorporate all benefits and costs within a market, N government intervention almost always causes a DEADWEIGHT LOSS. questions in PART A deal with perfectly competitive markets with no externalities. Please keep in mind assumptions that we are making while you are doing questions. Ask yourself, how will my answers change if supply was perfectly inelastic? If supply was perfectly elastic? If demand was perfectly inelastic? If demand was perfectly elastic?