The correct answer as to which condition must be met in order for an equation to be balanced would be that the number of atoms in the reactants equals the number of atoms in the products.
In a reaction, the law of conservation of matter, mass. or atom must always hold true. For an equation of a reaction to be balanced, the number of atoms of each element in the reactants must equal to the number of atoms of the elements in the products respectively, even though their states might have changed.
For example in the reaction below:
NaOH + HCl ---> NaCl + H2O
The number of atoms of Na, O, H, and Cl on the reactant side is the same as the product side of the equation. The equation is, thus, said to be balanced.
More on balanced equation can be found here: https://brainly.com/question/7181548
