When car engines run, they often produce toxic gases such as carbon monoxide (CO). Modern cars use a device called a catalytic converter to reduce the amount of carbon monoxide released into the environment. The catalytic converter combines carbon monoxide and oxygen (O2) to form carbon dioxide (CO2). While too much carbon dioxide can harm the environment, this gas is less toxic than carbon monoxide. In the chemical reaction described in the passage, which of the following are products?