Suppose government officials have set emissions tax to reduce pollution. Further suppose that with the emissions tax the marginal social cost of pollution exceeds the marginal social benefit of pollution. The emissions tax is

The emissions tax is too Low.

Marginal cost indicates the level of sacrifice that we need to choose a certain decision and marginal benefits indicates the level of benefit that we would receive when choosing a certain decision.

If the marginal cost of the pollution exceeds the marginal benefit, we could conclude that we're not doing enough effort as a response.