What is the best way to reduce carbon emissions?

CA has outlawed gasoline powered cars and truck effective 2025 (WSJ, Sept. 2020). The purported goal is to reduce carbon emissions. Five questions come to mind.

1. What is the best way to reduce carbon emissions?
1. Banning gasoline powered cars and trucks.
2. Subsidizing green vehicles.
3. Imposing a carbon tax. The revenues could flow to the general budget, be earmarked for green initiatives, or be refunded to taxpayers on a per capita basis as a carbon dividend. 
2. Which of the three options would have a bigger impact on carbon emissions?
3. How much will banning gasoline powered cars and trucks in CA, or even in the USA, affect climate change?
4. Who loses if drivers pay a tax sufficient to compensate people for the externality they create when they burn gasoline?
5. Who loses if a law forbids drivers from purchasing a gasoline-powered car and the drivers are willing to pay a tax sufficient to compensate people for the externality they create when they burn gasoline?