Final answer:
The thermal energy from the heat source to the thermometer is transferred by radiation to the tin can, then by conduction through the water, and finally by convection as the heated water circulates.
Explanation:
The thermal energy from the heat source reaches the thermometer above a tin can of water through a sequence of heat transfer processes. Initially, radiation emanates from the heat source, which is absorbed by the tin can. The thermal energy is then transferred from the hot bottom of the can throughout the water by conduction, as molecules collide and pass on their energy. As the water heats, it undergoes convection, where warmer, less dense water rises while cooler, denser water sinks, creating a circulation that distributes the heat. The thermometer, hanging directly above, detects the heat primarily through radiation emitted from the hot air rising above the water. As such, the correct sequence for the thermal energy transfer from the heat source to the thermometer is Radiation to Conduction to Convection.