______ supports combustion.
A. Sodium bicarbonate
B. Hydrogen
C. Carbon dioxide
D. None of these

Hint: Well you should know that burning is a high-temperature exothermic redox chemical reaction between a fuel and an oxidant, usually atmospheric oxygen that produces oxidized gaseous products, in a mixture termed as smoke.

Complete step by step answer:
Generally, A combustion reaction is a major class of chemical reactions. Combustion usually occurs when a hydrocarbon reacts with oxygen to produce carbon dioxide and water.
Let us exactly know what combustion is and what are the essential conditions required for combustion.

Combustion: A process in which a substance reacts with oxygen to produce heat, light and carbon dioxide. The substance which is burned is known as combustible substance.
There are three essential conditions for the process of combustion:
a) Oxygen
b) Ignition temperature (heat)
c) Combustible substance

Oxygen: It is very necessary for the combustion process. If there is no oxygen then no combustion process will take place.

Ignition temperature: The minimum temperature at which a combustible substance can catch fire. To burn a combustible substance heat is supplied so that it reaches to its ignition temperature and catches fire.

Combustible substance: example wood, coal etc.
There are two main types of combustion reactions you should know.
1.) Complete combustion reaction: Also called "clean combustion", clean combustion is oxidation of a hydrocarbon that produces only carbon dioxide and water.
2.) Incomplete combustion reaction: Also called "dirty combustion", incomplete combustion is hydrocarbon oxidation that produces carbon monoxide and/or carbon (soot) in addition to carbon dioxide.
Therefore, oxygen supports combustion which is not given in the above options.

Hence, Option D is the required answer.

Note: Remember that hydrogen is a combustible gas but does not support combustion when there is no supply of oxygen. So do not get confused.