Temperature is defined as:

Temperature is fundamentally categorized as a measure of the average kinetic energy of the molecules within a substance. This measurement reflects how rapidly the molecules are moving and, therefore, how much thermal energy they possess. As the temperature increases, the molecules tend to move more vigorously, which correlates with a higher average kinetic energy.

This definition explains the relationship between temperature and thermal sensations, such as when we feel hot or cold, as it is akin to the movement and energy levels of the molecules in the matter we are interacting with.

The other options allude to varying aspects of thermodynamics and energy transfer but do not accurately encapsulate the essence of what temperature represents in scientific terms. While internal energy is a concept linked to temperature, it encompasses both kinetic and potential energies, making it broader than what temperature specifically measures.