With an environmental program that places a tax or charge per ton of emissions, which of the following is true? 1. firms have a choice: they can either reduce their emissions and not pay the tax, or continue to emit and pay the tax per ton of emissions.

2. with a tax or charge program, firms don't have a choice - they must pay the tax per unit of emissions.

3. firms are required by the program to install specific equipment that brings about the required reduction in emissions, thereby avoiding the tax.

4. most firms will choose to not pay the charges or taxes and take the chance that they will have to pay enforcement penalties.