If government regulators incorrectly estimate farmers’ marginal abatement costs at MAC_e < MAC, the quantity-based intervention would reduce pollution to POLL_B < POLL*, while the Pigouvian tax would increase pollution to POLL_C > POLL*. Because MAC is steep relative to the marginal cost of pollution MCP, the price mechanism is preferable to the quantity mechanism, as seen by comparing the resulting deadweight losses from the two interventions (Y < X).