I think the answer is A.
But I also think it could be D.
If I were to pick, probably A.
Answer:
The answer is friction
Explanation:
Friction is a force that opposes motion between two surfaces that are in contact.
It is okay for students to use cell phones between classes and during the lunch break, as long as they do not create a distraction or cause the student to be tardy for class.
The answer is synthetic because synthetic means a substance made by chemical synthesis to imitate a natural product.
