An empty paper cup is the same temperature as the air in the room. A student fills the cup with cold water. Which of the following describes how thermal energy is transferred?

Thermal energy is transferred from the cup to the cold water until they are at the same temperature

Explanation:

The second law of thermodynamics states that the entropy of an isolated system can only remain constant or increase, and  will have a decreased potential energy than its initial state and also indicating that heat, or thermal energy, can only spontaneously flow from a hotter body to a colder body so as to attain thermal equilibrium

Therefore since the cup and the water form a thermodynamic system, with water being the colder body and the cup being the relatively hotter body, thermal energy can only be transferred from the cup to the cold water until they both reach thermal equilibrium or until they are at the same temperature.