In the question "An iron nail is made up of particles. What is true about the particles?" The correct answer is "They stay in place and vibrate."
For the other answer options, iron nails are solid particles and in a solid, molecules are packed together (i.e. the space between them is very small) and do not move all over the place because of a strong force of attraction between them, and it keeps its shape and stays in place and vibrate.
