Answer:
Step-by-step explanation:
In any form of experimental research where data is being analyzed, there needs to be only one variable present and each group in the experiment needs to have the same factors and environment as the others. That way the single variable can be isolated and the data properly analyzed. That is why it is important for the mass of each food to be the same, since the foods are already different variables the rest of the factors in the experiment need to be the same including the mass of each food.