I need help understanding this is not a test but study material

Explanation:
The law of conservation of mass:
In a chemical reaction, the mass is neither created nor destroyed. In other words, the mass of any one element at the beginning of a reaction will equal the mass of that element at the end of the reaction.
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According to this task, the statement that demonstrates the law of conservation of mass is:
Answer: there are 10 aluminum (Al) atoms represented on each side of the equation.