The correct option is B C (s) + O2 (g) →CO2 (g)
To represent a chemical reaction, a chemical equation is written with the reactants on the left hand side and the products on the right hand side of an arrow, going from left to right.
A + B → C
In the given reaction, reactants are charcoal, a solid and oxygen, a gas; which form carbon dioxide gas as the product. The chemical equation can be written as:
C (s) + O2 (g) →CO2 (g)