The correct answer is B. The particles in each are in constant motion.
While the three states of matter (solids, liquids, and gases) have distinct characteristics regarding particle arrangement and movement, they all share the common feature that the particles are in constant motion, albeit at different rates and forms of movement depending on the state.
Option A is incorrect because only solids have particles in fixed positions.
Option C is incorrect because only liquids and gases take the shape of their containers, while solids maintain a fixed shape.
Option D is misleading because solids have a definite volume, while liquids and gases can take different volumes depending on the container.