Oxides are:
a. only formed during incomplete combustion.
b. products formed during combustion.
c. products formed during double replacement reactions.
d. reactants in combustion.

The correct answer is Option B.

Explanation:

Combustion reaction is defined as the chemical reaction in which a hydrocarbon reacts with oxygen gas to produce carbon dioxide gas and water molecule. The chemical equation for this reaction follows:

Incomplete combustion is defined as the reaction in which supply of oxygen is limited and carbon monoxide gas is also produced as a product. The chemical equation for this reaction follows:

Single displacement reaction is defined as the reaction in which more reactive element displaces a less reactive element.

Element C is more reactive than element A.

As, we can see that oxides are the products in both complete combustion reaction and incomplete combustion reaction.

Hence, the correct answer is Option B.