Which statement reflects the kinetic theory of matter?

• A. All matter is made of tiny particles; the higher the temperature, the faster they move
• B. Energy cannot be created or destroyed, but it can be transferred from one form to another
• C. Particles do not move
• D. Size of particles never affects speed

Answer: (A)

The kinetic theory says matter is made of tiny particles that are always moving and colliding, and the temperature of a substance reflects the average kinetic energy of those particles. So when temperature goes up, those particles gain energy and move faster on average. That idea is exactly what the statement expresses: matter is composed of tiny particles, and higher temperature means faster particle movement.

This fits because it connects what we can’t see—particles zipping around—with what we can measure—temperature—in a single idea. The other statements miss or contradict this picture: energy being conserved is a general law about energy—not the behavior of particles in matter; saying particles don’t move contradicts the very premise that particles are in motion; and claiming size never affects speed ignores that heavier (or larger) particles require more energy to reach the same speed, so at the same temperature not all particles move at the same speed.