What do you think could be done to reduce levels of carbon dioxide in the atmosphere?

We cant really take away the carbon dioxide that is already present in the atmosphere unless with very advanced technologies but we can surely reduce the production level.

The production of carbon dioxide is mostly from the burning of fossil fuels and the gas produced by factories or vehicles.

As ourselves, we may not be able to stop the factories from producing gas and burning fuel but there are still something that we can do to help a bit. For example, turn off the electrical appliances when we're not using. This can save electricity thus to reduce the burning of fossil fuels. Or we can also take public transport instead of private vehicles to reduce the amout or carbon dioxide given out.

As the government, they should set up laws to control the gas produced by factories and vehicles, such as examining the gas content.

Your answer is going to be b.