A bridge usually has expansion joints. They allow the bridge to become slightly longer when it experiences thermal expansion. Look at the diagram of the bridge joint. A connection point on a bridge made of interlocking metal grooves

When the weather becomes cool, the “teeth” of the joint move away from each other. When the weather becomes warm, they move toward each other. Which statement is true about the particles that make up the bridge?

A. When the sides of the joint are close together, the particles have more kinetic energy than they do when the sides are farther apart.
B. When the sides of the joint are far apart, the particles have more kinetic energy than they do when the sides are closer together.
C. The particles contain the same amount of kinetic energy no matter how much the bridge has expanded.
D. The kinetic energy of the particles changes, but the amount it changes does not depend on the temperature of the bridge.