Temperature is a measure of:

Temperature is fundamentally defined as a measure of the average kinetic energy of the individual particles in a substance. This is rooted in the kinetic theory of gases, which posits that the temperature of a substance increases as the average speed of its particles increases. Therefore, higher temperatures indicate that the particles are moving more vigorously and have higher kinetic energy.

For instance, in a gas, the temperature is directly correlated with how fast the gas molecules are moving. As the temperature rises, these molecules collide with each other more frequently and with greater force, which directly reflects an increase in their average kinetic energy.

While total energy, potential energy, and energy stored in a compressed gas can all relate to the state of a system, they do not specifically measure temperature. Total energy includes both kinetic and potential energy, while potential energy relates to the position of particles, and the energy in a compressed gas is influenced by both pressure and volume—not just temperature alone. Hence, the correct answer focuses specifically on the relationship between temperature and the average kinetic energy of particles.