Which best describes thermal energy?

it is the difference between internal energies of two or more substances.

it is the sum of internal energies of two or more substances.

it is the portion of internal energy that can be transferred from one substance to another.

it is the portion of potential energy that can be transferred from one substance to another.

For the answer tot the question above, it is Thermal energy is the portion of internal energy that can be transferred from one substance to another. It is the energy that comes from heat. This is generated by the movement of the particles in an object.
Thermal energy is the energy and object or system has due to the movement of particles within. This results in the object or system having an internal temperature that can be measured with a thermometer.