Answer : The correct option is, The substances
and
are reactants that react to form the products
and
.
Explanation :
Balanced chemical reaction : It is defined as the number of atoms of individual elements present on reactant side must be equal to the number of atoms of individual elements present on product side.
In the balanced chemical reaction, the species present on left side of the right arrow are reactants and the species present on right side of the right arrow are products.
The given chemical reaction is:

The given chemical reaction is a balanced chemical reaction.
In this chemical reaction, the reactants are
and products are
.
Therefore,
and
are reactants that react to form the products
and
.