Answer:
A, maybe b or d
Step-by-step explanation:
A because thermal energy is caused by the friction between particles so A is true. B as if you decrease space between particles then they will collide more increasing friction and therefore thermal energy and exactly the same the opposite way round. With D. If you increase the amount of particles then there are more to collide with each other and less space however this one is tricky as it also depends on whether the space increases or not. I would say A and B, they are more safe but C is also maybe true but more risky. C definitely not as the particles movement direction does not affect thermal energy. Hope this helps. Please let me know if this was correct.