A student writes the following claim after an experiment:
"When two substances reach thermal equilibrium, their particles stop moving because there is no more heat to transfer."
Which response most accurately evaluates the student’s claim?
(a) The claim is correct because heat is the motion of particles, so if no heat is being transferred the particles must be at rest.
(b) The claim is incorrect because at equilibrium the particles of both substances all speed up to the same kinetic energy, removing the heat gradient.
(c) The claim is incorrect because the particles of both substances continue to move; thermal equilibrium only means there is no net transfer of energy as heat.
(d) The claim is partially correct: translational motion halts at equilibrium, but the particles still vibrate in place.