Final answer:
Heat transfer increases the thermal energy of a colder object by moving energy from the warmer surrounding air to the object, raising its temperature until thermal equilibrium is reached.
Step-by-step explanation:
The correct answer to how heat affects the thermal energy of a colder object is B: Heat causes the thermal energy of the object to increase as energy moves from the warmer air to the colder object. When heat is transferred, energy is spontaneously moved from a hotter substance (with higher kinetic energy) to a colder one with lower kinetic energy. This process increases the thermal energy of the colder object and thus raises its temperature. The transfer of thermal energy continues until thermal equilibrium is achieved, meaning both objects reach the same temperature.