In Summarizing the Research on the Externalities Associated with Driving

In summarizing the research on the externalities associated with driving cars, a 2007 Journal of Economic Literature article concluded that the optimal corrective tax on gasoline in the United States, in 2012 dollars, would be about

A) $0.40 per gallon.
B) $0.90 per gallon.
C) $2.10 per gallon.
D) $2.70 per gallon.