Available options:
+ wind and erosion;
+ pressure differences.;
+ refract or absorb.;
+ heat is produced;
+ electron transport;
+ depress neuronal excitability;
+ degrees Celsius;
+ 2 substances rubbing together;

You are presented with the quiz "what causes an object to lose energy" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "friction causes an object to lose energy" and "friction occurs when two substances rub together". So, what's the best answer to the question?
Answer:
2 substances rubbing together