Answer: Option (c) is the correct answer.
Step-by-step explanation:
According to law of conservation of mass, mass can neither be created nor it can be destroyed but it can be transformed from one form to another.
Therefore, when liquid plastic is frozen then then its molecules become closer to each other as a result, it changes into solid state.
But it will still weigh the same as there will be no effect on its mass.
Thus, we can conclude that plastic after the change will still weigh 15 grams.