Answer:
C
Step-by-step explanation:
First of all, the law of conservation of matter states that " In an ordinary chemical reaction, the mass of the products is equal to the mass of the reactants."
So, the answer should be C since the mass of Al and O₂ is equal on both the reactant's and product's side.
4Al + 3O₂ → 2Al₂O₃
Reactants Side: 4 aluminum and 6(3*2) oxygen
Products Side: 4(2*2) aluminum and 6(2*3) oxygen