Final answer:
The incorrect statement is that Australia has a carbon tax; as of early 2023, Australia does not have a carbon tax system though it did have one briefly in the past.
Step-by-step explanation:
The statement that is incorrect is D) Australia has a carbon tax. As of the knowledge cutoff in early 2023, Australia does not have a carbon tax system in place. The country had previously implemented a carbon pricing mechanism in 2012, but it was repealed in 2014. The other statements regarding British Columbia's carbon tax being $30 per tonne as of 2012 and it being revenue-neutral are correct. The statement regarding the high gas tax in the United Kingdom having an impact on carbon emissions by affecting driving behavior is also correct.