Answer:
The third choice
Step-by-step explanation:
The law of conservation of mass tells us that the mass of the reactants and products in a chemical reaction will be equal to one another. Equations follow the law of conservation of mass when they are balanced, which means that they have the same number and type of atoms on each side.
When individual atoms are counted, the third choice has the same number and type of atoms on each side: 1 gallium, three cesium and three fluorine.