Here's an elaboration on the gases often released during incomplete combustion:

Carbon Dioxide (CO2): Incomplete combustion can still produce carbon dioxide (CO2). While CO2 is a product of combustion, incomplete combustion may lead to a higher concentration of CO2 due to inefficient burning of the fuel.

Carbon Monoxide (CO): Carbon monoxide is a dangerous byproduct of incomplete combustion. It is a colorless, odorless gas that can be harmful when inhaled in large quantities. CO forms when there is insufficient oxygen to convert carbon to carbon dioxide.

Hydrocarbons: Hydrocarbons are compounds consisting of hydrogen and carbon, and they are found in various fuels. Incomplete combustion can lead to the release of hydrocarbons into the atmosphere. 

Lead (Pb): While lead is not typically a product of combustion, some older fuels, such as leaded gasoline, contained lead compounds as additives. These compounds could be released into the environment during combustion.

In contrast, oxygen and hydrogen are not usually released during incomplete combustion. Oxygen is consumed during combustion, and hydrogen, if present in the fuel, may combine with oxygen to form water vapor (H2O) during complete combustion.

THEREFORE THE CORRECT OPTION IS [1].